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|---|---|---|---|---|---|---|---|---|---|---|---|---|
A000901 | Number of solutions to the rook problem on a 2n X 2n board having a certain symmetry group (see Robinson for details). | [
"0",
"0",
"7",
"74",
"882",
"11144",
"159652",
"2571960",
"46406392",
"928734944",
"20436096048",
"490489794464",
"12752891909920",
"357081983435904",
"10712466529388608",
"342798976818878336",
"11655165558112403328",
"419585962575107694080"
] | [
"nonn",
"nice"
] | 31 | 1 | 3 | null | [
"M4446",
"N1881"
] | N. J. A. Sloane, Robert G. Wilson v | 2018-01-10T16:05:06 | oeisdata/seq/A000/A000901.seq | 1916d7cdcb9379d374b54aa93993d674 |
A000902 | Expansion of e.g.f. (1/2)*(exp(2*x + x^2) + 1). | [
"1",
"1",
"3",
"10",
"38",
"156",
"692",
"3256",
"16200",
"84496",
"460592",
"2611104",
"15355232",
"93376960",
"585989952",
"3786534784",
"25152768128",
"171474649344",
"1198143415040",
"8569374206464",
"62668198184448",
"468111364627456",
"3568287053001728"
] | [
"nonn",
"easy",
"nice",
"changed"
] | 63 | 0 | 3 | [
"A000898",
"A000902"
] | [
"M2853",
"N1147"
] | N. J. A. Sloane, Simon Plouffe | 2025-04-14T07:38:21 | oeisdata/seq/A000/A000902.seq | 93cadf17601c932026d40374e9dbe6d5 |
A000903 | Number of inequivalent ways of placing n nonattacking rooks on n X n board up to rotations and reflections of the board. | [
"1",
"1",
"2",
"7",
"23",
"115",
"694",
"5282",
"46066",
"456454",
"4999004",
"59916028",
"778525516",
"10897964660",
"163461964024",
"2615361578344",
"44460982752488",
"800296985768776",
"15205638776753680",
"304112757426239984",
"6386367801916347184"
] | [
"nonn",
"nice"
] | 70 | 1 | 3 | [
"A000085",
"A000142",
"A000903",
"A005635",
"A037223",
"A037224",
"A099952",
"A263685"
] | [
"M1761",
"N0698"
] | N. J. A. Sloane | 2025-02-16T08:32:21 | oeisdata/seq/A000/A000903.seq | 0b246b5fb6ca5d4883b5e6debd910e98 |
A000904 | a(n) = (n+1)*a(n-1) + (n+2)*a(n-2) + a(n-3); a(1)=0, a(2)=3, a(3)=13. | [
"0",
"3",
"13",
"83",
"592",
"4821",
"43979",
"444613",
"4934720",
"59661255",
"780531033",
"10987095719",
"165586966816",
"2660378564777",
"45392022568023",
"819716784789193",
"15620010933562688",
"313219935456042955",
"6593238655510464741",
"145364470356686267259",
"3349976056859294611696"
] | [
"nonn",
"nice",
"easy",
"changed"
] | 111 | 1 | 2 | [
"A000179",
"A000271",
"A000904"
] | [
"M2955",
"N1193"
] | N. J. A. Sloane | 2025-04-14T07:38:05 | oeisdata/seq/A000/A000904.seq | daf9e84066e252d73841871c420682e7 |
A000905 | Hamilton numbers. | [
"2",
"3",
"5",
"11",
"47",
"923",
"409619",
"83763206255",
"3508125906290858798171",
"6153473687096578758448522809275077520433167",
"18932619208894981833333582059033329370801266249535902023330546944758507753065602135843"
] | [
"nonn",
"nice",
"easy"
] | 77 | 1 | 1 | [
"A000905",
"A001660",
"A006719",
"A134294"
] | [
"M0736",
"N0275"
] | N. J. A. Sloane | 2023-03-01T15:33:46 | oeisdata/seq/A000/A000905.seq | 0a6ca1e4e274340dfc154c9c0f43995b |
A000906 | Exponential generating function: 2*(1+3*x)/(1-2*x)^(7/2). | [
"2",
"20",
"210",
"2520",
"34650",
"540540",
"9459450",
"183783600",
"3928374450",
"91662070500",
"2319050383650",
"63246828645000",
"1849969737866250",
"57775977967207500",
"1918987839625106250",
"67548371954803740000",
"2511955082069264081250"
] | [
"nonn"
] | 50 | 0 | 1 | [
"A000457",
"A000906",
"A001147",
"A051577",
"A098503"
] | [
"M2124",
"N0841"
] | N. J. A. Sloane | 2022-09-08T08:44:28 | oeisdata/seq/A000/A000906.seq | d5ddc52a493acd338c0ae67ad1525c44 |
A000907 | Second-order reciprocal Stirling number (Fekete) a(n) = [[2n+2, n]]. The number of n-orbit permutations of a (2n+2)-set with at least 2 elements in each orbit. Also known as associated Stirling numbers of the first kind (e.g., Comtet). | [
"6",
"130",
"2380",
"44100",
"866250",
"18288270",
"416215800",
"10199989800",
"268438920750",
"7562120816250",
"227266937597700",
"7262844156067500",
"246045975136211250",
"8810836639999143750",
"332624558868351750000",
"13205706717164131170000"
] | [
"nonn"
] | 50 | 1 | 1 | [
"A000483",
"A000907",
"A001784",
"A001785"
] | [
"M4298",
"N1797"
] | N. J. A. Sloane | 2023-08-05T13:08:12 | oeisdata/seq/A000/A000907.seq | 289bdce008d842a915a9df1e89034523 |
A000908 | Atom-rooted polyenoids with n edges with symmetry class C_s. | [
"0",
"0",
"1",
"4",
"14",
"47",
"164",
"565",
"1982",
"6977",
"24850",
"89082",
"321855",
"1169853",
"4276923",
"15713799",
"57998270",
"214934984",
"799473752",
"2983682702",
"11169374372",
"41929478873",
"157807392886",
"595340271682",
"2250901007539",
"8527699269192",
"32369066434276"
] | [
"nonn"
] | 24 | 0 | 4 | [
"A000908",
"A000912",
"A000913",
"A000935",
"A000936",
"A000941",
"A000942",
"A000947",
"A000948",
"A000953",
"A003446",
"A063786"
] | null | E. K. Lloyd (E.K.Lloyd(AT)soton.ac.uk) | 2023-02-16T14:54:05 | oeisdata/seq/A000/A000908.seq | 20fb56c9bb276630ede229a313044d61 |
A000909 | a(n) = (2n)!(2n+1)! / n!^2. | [
"1",
"12",
"720",
"100800",
"25401600",
"10059033600",
"5753767219200",
"4487938430976000",
"4577697199595520000",
"5914384781877411840000",
"9439358111876349296640000",
"18236839872145106841108480000",
"41944731705933745734549504000000"
] | [
"nonn"
] | 23 | 0 | 2 | [
"A000909",
"A079484"
] | null | N. J. A. Sloane | 2017-04-01T04:51:04 | oeisdata/seq/A000/A000909.seq | 559f80bead648f20f87b241553754718 |
A000910 | a(n) = 5*binomial(n, 6). | [
"0",
"0",
"0",
"0",
"0",
"0",
"5",
"35",
"140",
"420",
"1050",
"2310",
"4620",
"8580",
"15015",
"25025",
"40040",
"61880",
"92820",
"135660",
"193800",
"271320",
"373065",
"504735",
"672980",
"885500",
"1151150",
"1480050",
"1883700",
"2375100",
"2968875",
"3681405",
"4530960",
"5537840",
"6724520",
"8115800",
"9738960",
"11623920",
"13803405"
] | [
"nonn",
"easy"
] | 42 | 0 | 7 | [
"A000579",
"A000910",
"A080159",
"A088617",
"A210569"
] | [
"M3973",
"N1643"
] | N. J. A. Sloane | 2022-07-19T05:46:36 | oeisdata/seq/A000/A000910.seq | 327ddcbe554a79b838bf0d382ad99a67 |
A000911 | a(n) = (2n+3)! /( n! * (n+1)! ). | [
"6",
"60",
"420",
"2520",
"13860",
"72072",
"360360",
"1750320",
"8314020",
"38798760",
"178474296",
"811246800",
"3650610600",
"16287339600",
"72129646800",
"317370445920",
"1388495700900",
"6044040109800",
"26190840475800",
"113034153632400",
"486046860619320",
"2083057974082800",
"8900338616535600"
] | [
"nonn"
] | 50 | 0 | 1 | [
"A000217",
"A000911",
"A000984",
"A001801",
"A002802",
"A051133",
"A086466",
"A093602"
] | null | N. J. A. Sloane | 2020-10-13T03:54:01 | oeisdata/seq/A000/A000911.seq | aa34a431e3176d93bac7a3a6e7948101 |
A000912 | Expansion of (sqrt(1-4x^2) - sqrt(1-4x))/(2x). | [
"1",
"0",
"2",
"4",
"14",
"40",
"132",
"424",
"1430",
"4848",
"16796",
"58744",
"208012",
"742768",
"2674440",
"9694416",
"35357670",
"129643360",
"477638700",
"1767258328",
"6564120420",
"24466250224",
"91482563640",
"343059554864",
"1289904147324",
"4861946193440",
"18367353072152"
] | [
"nonn"
] | 29 | 0 | 3 | null | null | E. K. Lloyd (E.K.Lloyd(AT)soton.ac.uk) | 2017-09-03T13:29:07 | oeisdata/seq/A000/A000912.seq | 737306a2155eef582319a4b31d9eefa2 |
A000913 | Number of bond-rooted polyenoids with n edges. | [
"0",
"1",
"2",
"12",
"38",
"143",
"490",
"1768",
"6268",
"22610",
"81620",
"297160",
"1086172",
"3991995",
"14731290",
"54587280",
"202992808",
"757398510",
"2834493948",
"10637507400",
"40023577524",
"150946230006",
"570534370692",
"2160865067312",
"8199710635816"
] | [
"nonn"
] | 32 | 1 | 3 | [
"A000108",
"A000913"
] | null | E. K. Lloyd (E.K.Lloyd(AT)soton.ac.uk) | 2023-12-10T11:10:38 | oeisdata/seq/A000/A000913.seq | b88d5ca5923210cee2f6b742f015d6a4 |
A000914 | Stirling numbers of the first kind: s(n+2, n). | [
"0",
"2",
"11",
"35",
"85",
"175",
"322",
"546",
"870",
"1320",
"1925",
"2717",
"3731",
"5005",
"6580",
"8500",
"10812",
"13566",
"16815",
"20615",
"25025",
"30107",
"35926",
"42550",
"50050",
"58500",
"67977",
"78561",
"90335",
"103385",
"117800",
"133672",
"151096",
"170170",
"190995",
"213675",
"238317",
"265031"
] | [
"nonn",
"easy",
"nice"
] | 143 | 0 | 2 | [
"A000217",
"A000290",
"A000914",
"A001296",
"A006325",
"A008275",
"A033428",
"A033581",
"A033583",
"A052149",
"A241765"
] | [
"M1998",
"N0789"
] | N. J. A. Sloane | 2025-03-06T14:51:19 | oeisdata/seq/A000/A000914.seq | 5a0dda9dc72d500e02e4aaa66206144d |
A000915 | Stirling numbers of first kind s(n+4, n). | [
"24",
"274",
"1624",
"6769",
"22449",
"63273",
"157773",
"357423",
"749463",
"1474473",
"2749747",
"4899622",
"8394022",
"13896582",
"22323822",
"34916946",
"53327946",
"79721796",
"116896626",
"168423871",
"238810495",
"333685495",
"460012995",
"626334345",
"843041745",
"1122686019",
"1480321269",
"1933889244"
] | [
"nonn",
"easy"
] | 59 | 1 | 1 | [
"A000915",
"A001298",
"A001303",
"A008275",
"A053567",
"A094216"
] | [
"M5155",
"N2239"
] | N. J. A. Sloane | 2022-10-21T22:07:55 | oeisdata/seq/A000/A000915.seq | a33f22a232aeff695098a9dc3fff3d5a |
A000916 | a(2n) = n+2, a(2n-1) = smallest number requiring n+2 letters in English. | [
"1",
"3",
"4",
"4",
"3",
"5",
"11",
"6",
"15",
"7",
"13",
"8",
"17",
"9",
"24",
"10",
"23",
"11",
"73",
"12",
"3000",
"13",
"11000",
"14",
"15000",
"15",
"101",
"16",
"104",
"17",
"103",
"18",
"111",
"19",
"115",
"20",
"113",
"21",
"117",
"22",
"124",
"23",
"123",
"24",
"173",
"25",
"323",
"26",
"373",
"27",
"1104",
"28",
"1103",
"29",
"1111",
"30"
] | [
"nonn",
"word",
"easy"
] | 10 | 1 | 2 | [
"A000916",
"A001166",
"A014388",
"A045494",
"A045495"
] | null | Jacques Haubrich (jhaubrich(AT)freeler.nl) | 2012-03-30T18:39:33 | oeisdata/seq/A000/A000916.seq | 6a1ec3c5b4f60557423184353e291306 |
A000917 | a(n) = (2n+3)!/(n!*(n+2)!). | [
"3",
"20",
"105",
"504",
"2310",
"10296",
"45045",
"194480",
"831402",
"3527160",
"14872858",
"62403600",
"260757900",
"1085822640",
"4508102925",
"18668849760",
"77138650050",
"318107374200",
"1309542023790",
"5382578744400",
"22093039119060",
"90567738003600",
"370847442355650",
"1516927277253024"
] | [
"nonn",
"easy"
] | 53 | 0 | 1 | [
"A000108",
"A000302",
"A000917",
"A000984",
"A001622",
"A001791",
"A003506",
"A007054",
"A038665",
"A038679",
"A061928",
"A073010"
] | null | N. J. A. Sloane | 2022-09-08T08:44:28 | oeisdata/seq/A000/A000917.seq | 0180df6e541d7a0ce2f73f1d85ed1224 |
A000918 | a(n) = 2^n - 2. | [
"-1",
"0",
"2",
"6",
"14",
"30",
"62",
"126",
"254",
"510",
"1022",
"2046",
"4094",
"8190",
"16382",
"32766",
"65534",
"131070",
"262142",
"524286",
"1048574",
"2097150",
"4194302",
"8388606",
"16777214",
"33554430",
"67108862",
"134217726",
"268435454",
"536870910",
"1073741822",
"2147483646",
"4294967294",
"8589934590",
"17179869182",
"34359738366",
"68719476734",
"137438953470"
] | [
"sign",
"easy"
] | 341 | 0 | 3 | [
"A000225",
"A000325",
"A000918",
"A000919",
"A001117",
"A001118",
"A026998",
"A033484",
"A058809",
"A095121",
"A095151",
"A110146",
"A125128"
] | [
"M1599",
"N0625"
] | N. J. A. Sloane | 2025-02-16T08:32:22 | oeisdata/seq/A000/A000918.seq | 77915986218aec9f8f9834a1a8f85ea1 |
A000919 | a(n) = 4^n - C(4,3)*3^n + C(4,2)*2^n - C(4,1). | [
"0",
"0",
"0",
"24",
"240",
"1560",
"8400",
"40824",
"186480",
"818520",
"3498000",
"14676024",
"60780720",
"249401880",
"1016542800",
"4123173624",
"16664094960",
"67171367640",
"270232006800",
"1085570781624",
"4356217681200",
"17466686971800",
"69992221794000",
"280345359228024",
"1122510953731440"
] | [
"nonn",
"easy"
] | 85 | 1 | 4 | [
"A000919",
"A001117",
"A001118",
"A019538"
] | [
"M5151",
"N2235"
] | N. J. A. Sloane | 2025-02-19T11:51:57 | oeisdata/seq/A000/A000919.seq | 40745faea26702f8c2bdfa0a167dee51 |
A000920 | Differences of 0: 6!*Stirling2(n,6). | [
"0",
"0",
"0",
"0",
"0",
"720",
"15120",
"191520",
"1905120",
"16435440",
"129230640",
"953029440",
"6711344640",
"45674188560",
"302899156560",
"1969147121760",
"12604139926560",
"79694820748080",
"499018753280880",
"3100376804676480",
"19141689213218880",
"117579844328562000"
] | [
"nonn",
"easy"
] | 69 | 1 | 6 | [
"A000770",
"A000918",
"A000919",
"A000920",
"A001117",
"A001118",
"A019538"
] | [
"M5473",
"N2370"
] | N. J. A. Sloane | 2024-08-26T04:38:38 | oeisdata/seq/A000/A000920.seq | f32f96657b577b94d5ad280eeaf25c56 |
A000921 | Primes p of the form 3k+1 such that Sum_{x=1..p} cos(2*Pi*x^3/p) > sqrt(p). | [
"7",
"31",
"43",
"67",
"73",
"79",
"103",
"127",
"163",
"181",
"223",
"229",
"271",
"277",
"307",
"313",
"337",
"349",
"409",
"421",
"439",
"457",
"463",
"499",
"523",
"577",
"643",
"661",
"673",
"691",
"709",
"727",
"757",
"769",
"811",
"823",
"829",
"853",
"877",
"919",
"967",
"991",
"997",
"1021",
"1069",
"1087",
"1093",
"1117",
"1123",
"1171",
"1213"
] | [
"nonn"
] | 42 | 1 | 1 | [
"A000921",
"A000922",
"A000923",
"A002476"
] | [
"M4398",
"N1854"
] | N. J. A. Sloane | 2023-12-12T08:22:45 | oeisdata/seq/A000/A000921.seq | 927e34fee98b5ab78910e89f4b5bdb00 |
A000922 | Primes p of the form 3k+1 such that -sqrt(p) < sum_{x=1..p} cos(2*Pi*x^3/p) < sqrt(p). | [
"13",
"19",
"37",
"61",
"109",
"157",
"193",
"241",
"283",
"367",
"373",
"379",
"397",
"487",
"571",
"613",
"619",
"733",
"739",
"859",
"883",
"907",
"1009",
"1033",
"1051",
"1129",
"1153",
"1201",
"1291",
"1297",
"1303",
"1399",
"1429",
"1453",
"1459",
"1489",
"1549",
"1669",
"1699",
"1753",
"1783",
"1831",
"1861",
"1933",
"1951",
"1987",
"2011"
] | [
"nonn"
] | 21 | 1 | 1 | [
"A000921",
"A000922",
"A000923",
"A002476"
] | [
"M4890",
"N2096"
] | N. J. A. Sloane | 2017-10-19T03:13:42 | oeisdata/seq/A000/A000922.seq | a9943c436d0f7e660725037718341aa9 |
A000923 | Primes p of the form 3k+1 such that sum_{x=1..p} cos(2*Pi*x^3/p) < -sqrt(p). | [
"97",
"139",
"151",
"199",
"211",
"331",
"433",
"541",
"547",
"601",
"607",
"631",
"751",
"787",
"937",
"1039",
"1063",
"1249",
"1321",
"1327",
"1381",
"1471",
"1483",
"1663",
"1693",
"1741",
"1747",
"1879",
"1999",
"2113",
"2143",
"2377",
"2437",
"2503",
"2521",
"2557",
"2593",
"2677",
"2797",
"2857",
"2887",
"3019",
"3121",
"3313",
"3331",
"3361"
] | [
"nonn"
] | 18 | 1 | 1 | [
"A000921",
"A000922",
"A000923",
"A002476"
] | [
"M5365",
"N2331"
] | N. J. A. Sloane | 2017-10-19T03:13:42 | oeisdata/seq/A000/A000923.seq | b0b18080a86a76cb6a839fd74e4e1d50 |
A000924 | Class number of Q(sqrt(-n)), n squarefree. | [
"1",
"1",
"1",
"2",
"2",
"1",
"2",
"1",
"2",
"4",
"2",
"4",
"1",
"4",
"2",
"3",
"6",
"6",
"4",
"3",
"4",
"4",
"2",
"2",
"6",
"4",
"8",
"4",
"1",
"4",
"5",
"2",
"6",
"4",
"4",
"2",
"3",
"6",
"8",
"8",
"8",
"1",
"8",
"4",
"7",
"4",
"10",
"8",
"4",
"5",
"4",
"3",
"4",
"10",
"6",
"12",
"2",
"4",
"8",
"8",
"4",
"14",
"4",
"5",
"8",
"6",
"3",
"6",
"12",
"8",
"8",
"8",
"2",
"6",
"10",
"10",
"2",
"5",
"12",
"4",
"5",
"4",
"14",
"8",
"8",
"3",
"8",
"4",
"10",
"8",
"16",
"14",
"7",
"8",
"4",
"6",
"8",
"10"
] | [
"nonn",
"nice",
"easy"
] | 43 | 1 | 4 | [
"A000924",
"A003649",
"A005117",
"A033197"
] | [
"M0195",
"N0072"
] | N. J. A. Sloane, Mira Bernstein | 2021-12-22T00:10:28 | oeisdata/seq/A000/A000924.seq | 1d414b5eb37f30f9e18942229721c5c9 |
A000925 | Number of ordered ways of writing n as a sum of 2 squares of nonnegative integers. | [
"1",
"2",
"1",
"0",
"2",
"2",
"0",
"0",
"1",
"2",
"2",
"0",
"0",
"2",
"0",
"0",
"2",
"2",
"1",
"0",
"2",
"0",
"0",
"0",
"0",
"4",
"2",
"0",
"0",
"2",
"0",
"0",
"1",
"0",
"2",
"0",
"2",
"2",
"0",
"0",
"2",
"2",
"0",
"0",
"0",
"2",
"0",
"0",
"0",
"2",
"3",
"0",
"2",
"2",
"0",
"0",
"0",
"0",
"2",
"0",
"0",
"2",
"0",
"0",
"2",
"4",
"0",
"0",
"2",
"0",
"0",
"0",
"1",
"2",
"2",
"0",
"0",
"0",
"0",
"0",
"2",
"2",
"2",
"0",
"0",
"4",
"0",
"0",
"0",
"2",
"2",
"0",
"0",
"0",
"0",
"0",
"0",
"2",
"1",
"0",
"4"
] | [
"nonn",
"nice"
] | 30 | 0 | 2 | [
"A000161",
"A000290",
"A000925",
"A010052",
"A247367"
] | null | Jacques Haubrich (jhaubrich(AT)freeler.nl) | 2017-04-26T22:59:25 | oeisdata/seq/A000/A000925.seq | 06d7437fab0e0bbef5edba0c6fb27d8a |
A000926 | Euler's "numerus idoneus" (or "numeri idonei", or idoneal, or suitable, or convenient numbers). | [
"1",
"2",
"3",
"4",
"5",
"6",
"7",
"8",
"9",
"10",
"12",
"13",
"15",
"16",
"18",
"21",
"22",
"24",
"25",
"28",
"30",
"33",
"37",
"40",
"42",
"45",
"48",
"57",
"58",
"60",
"70",
"72",
"78",
"85",
"88",
"93",
"102",
"105",
"112",
"120",
"130",
"133",
"165",
"168",
"177",
"190",
"210",
"232",
"240",
"253",
"273",
"280",
"312",
"330",
"345",
"357",
"385",
"408",
"462",
"520",
"760",
"840",
"1320",
"1365",
"1848"
] | [
"nonn",
"fini",
"full",
"nice",
"changed"
] | 117 | 1 | 2 | [
"A000926",
"A014556",
"A025052",
"A026501",
"A093669",
"A094376",
"A094377",
"A094378",
"A139642"
] | [
"M0476",
"N0176"
] | N. J. A. Sloane | 2025-04-18T08:53:29 | oeisdata/seq/A000/A000926.seq | da180a4dbc67ba372b902b8c1496ac3e |
A000927 | "First factor" (or relative class number) h- for cyclotomic field Q( exp(2 Pi / prime(n)) ). | [
"1",
"1",
"1",
"1",
"1",
"1",
"1",
"1",
"3",
"8",
"9",
"37",
"121",
"211",
"695",
"4889",
"41241",
"76301",
"853513",
"3882809",
"11957417",
"100146415",
"838216959",
"13379363737",
"411322824001",
"3547404378125",
"9069094643165",
"63434933542623",
"161784800122409",
"1612072001362952",
"2604529186263992195",
"28496379729272136525",
"646901570175200968153",
"1753848916484925681747",
"687887859687174720123201",
"2333546653547742584439257",
"56234327700401832767069245",
"2708534744692077051875131636"
] | [
"nonn",
"nice"
] | 59 | 1 | 9 | [
"A000927",
"A055513",
"A061653"
] | [
"M2711",
"N1088"
] | N. J. A. Sloane | 2019-08-09T08:22:29 | oeisdata/seq/A000/A000927.seq | c5d0513b7d32ac788693ecabcb66b5c8 |
A000928 | Irregular primes: primes p such that at least one of the numerators of the Bernoulli numbers B_2, B_4, ..., B_{p-3} (A000367) is divisible by p. | [
"37",
"59",
"67",
"101",
"103",
"131",
"149",
"157",
"233",
"257",
"263",
"271",
"283",
"293",
"307",
"311",
"347",
"353",
"379",
"389",
"401",
"409",
"421",
"433",
"461",
"463",
"467",
"491",
"523",
"541",
"547",
"557",
"577",
"587",
"593",
"607",
"613",
"617",
"619",
"631",
"647",
"653",
"659",
"673",
"677",
"683",
"691",
"727",
"751",
"757",
"761",
"773",
"797",
"809",
"811",
"821",
"827",
"839",
"877",
"881",
"887",
"929",
"953",
"971",
"1061"
] | [
"nonn",
"nice",
"easy",
"changed"
] | 123 | 1 | 1 | [
"A000928",
"A007703",
"A061576",
"A091887"
] | [
"M5260",
"N2292"
] | N. J. A. Sloane | 2025-04-22T10:47:45 | oeisdata/seq/A000/A000928.seq | accbfa554642da6d34281bb27a53f248 |
A000929 | Dimension of n-th degree part of Steenrod algebra. | [
"1",
"1",
"1",
"2",
"2",
"2",
"3",
"4",
"4",
"5",
"6",
"6",
"7",
"8",
"9",
"11",
"12",
"13",
"15",
"16",
"17",
"20",
"22",
"23",
"26",
"28",
"29",
"32",
"35",
"37",
"41",
"45",
"47",
"51",
"55",
"58",
"63",
"68",
"72",
"77",
"82",
"86",
"92",
"98",
"103",
"111",
"118",
"123",
"131",
"139",
"145",
"154",
"164",
"171",
"180",
"190",
"198",
"208",
"219",
"229",
"241",
"253",
"264",
"278",
"291"
] | [
"nonn"
] | 59 | 0 | 4 | [
"A000041",
"A000225",
"A000929",
"A018819",
"A079559",
"A117145"
] | null | J. Daniel Christensen, Mar 15 1996 | 2021-03-15T15:33:37 | oeisdata/seq/A000/A000929.seq | 57b4010499c17032bf16663e9a6cb2d9 |
A000930 | Narayana's cows sequence: a(0) = a(1) = a(2) = 1; thereafter a(n) = a(n-1) + a(n-3). | [
"1",
"1",
"1",
"2",
"3",
"4",
"6",
"9",
"13",
"19",
"28",
"41",
"60",
"88",
"129",
"189",
"277",
"406",
"595",
"872",
"1278",
"1873",
"2745",
"4023",
"5896",
"8641",
"12664",
"18560",
"27201",
"39865",
"58425",
"85626",
"125491",
"183916",
"269542",
"395033",
"578949",
"848491",
"1243524",
"1822473",
"2670964",
"3914488",
"5736961",
"8407925"
] | [
"nonn",
"easy",
"nice",
"changed"
] | 598 | 0 | 4 | [
"A000045",
"A000073",
"A000079",
"A000213",
"A000930",
"A001609",
"A003269",
"A003520",
"A005708",
"A005709",
"A005710",
"A007318",
"A017898",
"A017904",
"A048715",
"A060576",
"A068921",
"A069241",
"A078012",
"A092526",
"A102547",
"A120562",
"A145580",
"A170954",
"A179070",
"A214551",
"A271901",
"A271953",
"A277627",
"A289207"
] | [
"M0571",
"N0207"
] | N. J. A. Sloane | 2025-04-18T22:27:28 | oeisdata/seq/A000/A000930.seq | 4c433a93c830d6672ead24456686003f |
A000931 | Padovan sequence (or Padovan numbers): a(n) = a(n-2) + a(n-3) with a(0) = 1, a(1) = a(2) = 0. | [
"1",
"0",
"0",
"1",
"0",
"1",
"1",
"1",
"2",
"2",
"3",
"4",
"5",
"7",
"9",
"12",
"16",
"21",
"28",
"37",
"49",
"65",
"86",
"114",
"151",
"200",
"265",
"351",
"465",
"616",
"816",
"1081",
"1432",
"1897",
"2513",
"3329",
"4410",
"5842",
"7739",
"10252",
"13581",
"17991",
"23833",
"31572",
"41824",
"55405",
"73396",
"97229",
"128801",
"170625"
] | [
"nonn",
"easy",
"nice"
] | 659 | 0 | 9 | [
"A000073",
"A000931",
"A001608",
"A005682",
"A005691",
"A020720",
"A078027",
"A096231",
"A103372",
"A103380",
"A106510",
"A124745",
"A133034",
"A134816",
"A145462",
"A146973",
"A153462",
"A164001",
"A182097",
"A228361",
"A291289"
] | [
"M0284",
"N0102"
] | N. J. A. Sloane | 2025-03-30T02:41:44 | oeisdata/seq/A000/A000931.seq | d8510766dfb4da69d4b5a4c396c8ec9d |
A000932 | a(n) = a(n-1) + n*a(n-2); a(0) = a(1) = 1. | [
"1",
"1",
"3",
"6",
"18",
"48",
"156",
"492",
"1740",
"6168",
"23568",
"91416",
"374232",
"1562640",
"6801888",
"30241488",
"139071696",
"653176992",
"3156467520",
"15566830368",
"78696180768",
"405599618496",
"2136915595392",
"11465706820800",
"62751681110208",
"349394351630208",
"1980938060495616"
] | [
"nonn",
"easy"
] | 84 | 0 | 3 | [
"A000085",
"A000932",
"A173895"
] | [
"M2595",
"N1025"
] | N. J. A. Sloane | 2022-08-21T06:35:42 | oeisdata/seq/A000/A000932.seq | 34a3f8c37cab72a9a4969a992a39c944 |
A000933 | Genus of complete graph on n nodes. | [
"0",
"0",
"0",
"0",
"1",
"1",
"1",
"2",
"3",
"4",
"5",
"6",
"8",
"10",
"11",
"13",
"16",
"18",
"20",
"23",
"26",
"29",
"32",
"35",
"39",
"43",
"46",
"50",
"55",
"59",
"63",
"68",
"73",
"78",
"83",
"88",
"94",
"100",
"105",
"111",
"118",
"124",
"130",
"137",
"144",
"151",
"158",
"165",
"173",
"181",
"188",
"196",
"205",
"213",
"221",
"230",
"239",
"248",
"257",
"266",
"276",
"286",
"295",
"305"
] | [
"easy",
"nonn",
"nice"
] | 75 | 1 | 8 | [
"A000933",
"A007997"
] | [
"M0503",
"N0182"
] | N. J. A. Sloane | 2025-02-16T08:32:22 | oeisdata/seq/A000/A000933.seq | d07f272df4d0d4fa376dc77d08deaab9 |
A000934 | Chromatic number (or Heawood number) Chi(n) of surface of genus n. | [
"4",
"7",
"8",
"9",
"10",
"11",
"12",
"12",
"13",
"13",
"14",
"15",
"15",
"16",
"16",
"16",
"17",
"17",
"18",
"18",
"19",
"19",
"19",
"20",
"20",
"20",
"21",
"21",
"21",
"22",
"22",
"22",
"23",
"23",
"23",
"24",
"24",
"24",
"24",
"25",
"25",
"25",
"25",
"26",
"26",
"26",
"27",
"27",
"27",
"27",
"28",
"28",
"28",
"28",
"28",
"29",
"29",
"29",
"29",
"30",
"30",
"30",
"30",
"31",
"31",
"31",
"31",
"31",
"32",
"32"
] | [
"easy",
"nice",
"nonn"
] | 65 | 0 | 1 | [
"A000703",
"A000934",
"A006343"
] | [
"M3292",
"N1327"
] | N. J. A. Sloane | 2025-02-16T08:32:22 | oeisdata/seq/A000/A000934.seq | 565bc2e50a09f3b1945e6bbfa2a3557c |
A000935 | Number of free planar polyenoids with 2n nodes and symmetry point group C_{2h}. | [
"0",
"1",
"2",
"7",
"20",
"63",
"191",
"598",
"1870",
"5906"
] | [
"nonn",
"more"
] | 19 | 1 | 3 | null | null | E. K. Lloyd (E.K.Lloyd(AT)soton.ac.uk) | 2015-10-16T10:00:34 | oeisdata/seq/A000/A000935.seq | 0e2ef6533a4b1a30da749c091cd7d524 |
A000936 | Number of free planar polyenoids with n nodes and symmetry point group C_{2v}. | [
"0",
"0",
"1",
"1",
"2",
"4",
"4",
"12",
"10",
"29",
"27",
"88",
"76",
"247",
"217",
"722",
"638",
"2134",
"1901",
"6413"
] | [
"nonn",
"more"
] | 13 | 1 | 5 | null | null | E. K. Lloyd (E.K.Lloyd(AT)soton.ac.uk) | 2015-10-14T14:53:32 | oeisdata/seq/A000/A000936.seq | cea16e78b51c0ac6a65fa73cb7723e5c |
A000937 | Length of longest simple cycle without chords in the n-dimensional hypercube graph. Also called n-coil or closed n-snake-in-the-box problem. | [
"0",
"4",
"6",
"8",
"14",
"26",
"48",
"96"
] | [
"nonn",
"nice",
"hard",
"more"
] | 86 | 1 | 2 | [
"A000937",
"A099155"
] | [
"M0995",
"N0373"
] | N. J. A. Sloane | 2025-02-16T08:32:22 | oeisdata/seq/A000/A000937.seq | 549210589bb261e81c940cc4c32e3470 |
A000938 | Number of collinear point-triples in an n X n grid. | [
"0",
"0",
"8",
"44",
"152",
"372",
"824",
"1544",
"2712",
"4448",
"6992",
"10332",
"15072",
"21012",
"28688",
"38520",
"50880",
"65480",
"83640",
"104676",
"130264",
"160556",
"195848",
"235600",
"282840",
"336384",
"397136",
"465876",
"544464",
"630684",
"729744",
"837744",
"958384",
"1091904",
"1238520",
"1400140",
"1581384",
"1776084"
] | [
"nonn",
"nice"
] | 57 | 1 | 3 | [
"A000769",
"A000938",
"A157882",
"A272651",
"A334704"
] | [
"M4527",
"N1919"
] | N. J. A. Sloane | 2020-06-19T23:50:05 | oeisdata/seq/A000/A000938.seq | 60c7ad4690ec19b0a58d8fad5c5b5d76 |
A000939 | Number of inequivalent n-gons. | [
"1",
"1",
"1",
"2",
"4",
"14",
"54",
"332",
"2246",
"18264",
"164950",
"1664354",
"18423144",
"222406776",
"2905943328",
"40865005494",
"615376173184",
"9880209206458",
"168483518571798",
"3041127561315224",
"57926238289970076",
"1161157777643184900",
"24434798429947993054",
"538583682082245127336"
] | [
"nonn",
"nice",
"easy"
] | 63 | 1 | 4 | [
"A000031",
"A000939",
"A000940",
"A002619",
"A002866",
"A006125",
"A008965",
"A059966",
"A060223",
"A094154",
"A094155",
"A192332",
"A231091",
"A275527",
"A323858",
"A323870",
"A324461"
] | [
"M1280",
"N0491"
] | N. J. A. Sloane | 2025-02-16T08:32:22 | oeisdata/seq/A000/A000939.seq | f8d5976b4f8ddd1a866b14bc7923c4df |
A000940 | Number of n-gons with n vertices. | [
"1",
"2",
"4",
"12",
"39",
"202",
"1219",
"9468",
"83435",
"836017",
"9223092",
"111255228",
"1453132944",
"20433309147",
"307690667072",
"4940118795869",
"84241805734539",
"1520564059349452",
"28963120073957838",
"580578894859915650",
"12217399235411398127",
"269291841184184374868",
"6204484017822892034404"
] | [
"nonn",
"easy",
"nice"
] | 110 | 3 | 2 | [
"A000939",
"A000940",
"A002619",
"A007619",
"A089066",
"A094156",
"A094157",
"A262480"
] | [
"M1260",
"N0482"
] | N. J. A. Sloane | 2022-11-23T08:57:10 | oeisdata/seq/A000/A000940.seq | d9c89fabee957efa5e091ccf9eb380b5 |
A000941 | Number of free planar polyenoids with n nodes and symmetry point group C_s. | [
"0",
"0",
"0",
"0",
"2",
"5",
"21",
"58",
"194",
"570",
"1790",
"5434",
"16924",
"52362",
"163784",
"512670",
"1614406",
"5096314",
"16150180"
] | [
"nonn",
"more"
] | 19 | 1 | 5 | null | null | E. K. Lloyd (E.K.Lloyd(AT)soton.ac.uk) | 2015-10-13T18:11:45 | oeisdata/seq/A000/A000941.seq | 6f0a875bb62151a2d526ece0321f31af |
A000942 | Number of free planar polyenoids with n nodes. | [
"1",
"1",
"1",
"3",
"4",
"12",
"26",
"77",
"204",
"624",
"1817",
"5585",
"17007",
"52803",
"164001",
"514009",
"1615044",
"5100324",
"16152134",
"51324864"
] | [
"nonn",
"more"
] | 17 | 1 | 4 | [
"A000942",
"A197459"
] | null | E. K. Lloyd (E.K.Lloyd(AT)soton.ac.uk) | 2020-07-12T08:23:25 | oeisdata/seq/A000/A000942.seq | 4d46eb395e3171913c07190b4ab2e8e2 |
A000943 | Number of combinatorial types of simplicial n-dimensional polytopes with n+3 nodes. | [
"1",
"2",
"5",
"8",
"18",
"29",
"57",
"96",
"183",
"318",
"604",
"1080",
"2047",
"3762",
"7145",
"13354",
"25471",
"48164",
"92193",
"175780",
"337581",
"647313",
"1246849",
"2400828",
"4636375",
"8956045",
"17334785",
"33570800",
"65108045",
"126355319",
"245492226",
"477284164",
"928772631",
"1808538336"
] | [
"nonn",
"nice"
] | 16 | 1 | 2 | [
"A000943",
"A000944",
"A049337"
] | [
"M1352",
"N0519"
] | N. J. A. Sloane | 2014-12-09T00:25:56 | oeisdata/seq/A000/A000943.seq | eec6d257df57eff2866c41dfa2f83411 |
A000944 | Number of polyhedra (or 3-connected simple planar graphs) with n nodes. | [
"0",
"0",
"0",
"1",
"2",
"7",
"34",
"257",
"2606",
"32300",
"440564",
"6384634",
"96262938",
"1496225352",
"23833988129",
"387591510244",
"6415851530241",
"107854282197058"
] | [
"nonn",
"nice",
"hard",
"more"
] | 53 | 1 | 5 | [
"A000944",
"A003094",
"A005470",
"A005841",
"A021103",
"A049334",
"A049336",
"A049337",
"A212438"
] | [
"M1796",
"N0709"
] | N. J. A. Sloane | 2025-02-16T08:32:22 | oeisdata/seq/A000/A000944.seq | 10d4a3c2c8f879cf3216d454f84e6bef |
A000945 | Euclid-Mullin sequence: a(1) = 2, a(n+1) is smallest prime factor of 1 + Product_{k=1..n} a(k). | [
"2",
"3",
"7",
"43",
"13",
"53",
"5",
"6221671",
"38709183810571",
"139",
"2801",
"11",
"17",
"5471",
"52662739",
"23003",
"30693651606209",
"37",
"1741",
"1313797957",
"887",
"71",
"7127",
"109",
"23",
"97",
"159227",
"643679794963466223081509857",
"103",
"1079990819",
"9539",
"3143065813",
"29",
"3847",
"89",
"19",
"577",
"223",
"139703",
"457",
"9649",
"61",
"4357"
] | [
"nonn",
"nice",
"hard"
] | 183 | 1 | 1 | [
"A000945",
"A000946",
"A005265",
"A005266",
"A051309",
"A051334",
"A051614",
"A051615",
"A051616",
"A056756"
] | [
"M0863",
"N0329"
] | N. J. A. Sloane | 2025-03-28T04:54:45 | oeisdata/seq/A000/A000945.seq | ef380375443c1887dafe24459d67d17e |
A000946 | Euclid-Mullin sequence: a(1) = 2, a(n+1) is the largest prime factor of 1 + Product_{k=1..n} a(k). | [
"2",
"3",
"7",
"43",
"139",
"50207",
"340999",
"2365347734339",
"4680225641471129",
"1368845206580129",
"889340324577880670089824574922371",
"20766142440959799312827873190033784610984957267051218394040721"
] | [
"nonn",
"nice"
] | 127 | 1 | 1 | [
"A000945",
"A000946",
"A005265",
"A005266",
"A216227"
] | [
"M0864",
"N0330"
] | N. J. A. Sloane | 2025-03-28T04:31:27 | oeisdata/seq/A000/A000946.seq | c4b649528f6c6d27b6e1932dab6734a8 |
A000947 | Number of free nonplanar polyenoids with n nodes and symmetry point group C_{2v}. | [
"1",
"2",
"4",
"10",
"15",
"44",
"56",
"177",
"212",
"706",
"792",
"2714",
"2961"
] | [
"nonn",
"more"
] | 18 | 7 | 2 | null | null | E. K. Lloyd (E.K.Lloyd(AT)soton.ac.uk) | 2015-10-16T03:15:40 | oeisdata/seq/A000/A000947.seq | f01fe0c548fa015740f164933e31d9d4 |
A000948 | Number of free nonplanar polyenoids with n nodes and symmetry point group C_s. | [
"0",
"3",
"20",
"99",
"450",
"1896",
"7771",
"30895",
"121144",
"468409",
"1796584",
"6841014",
"25925062"
] | [
"nonn",
"more"
] | 18 | 7 | 2 | null | null | E. K. Lloyd (E.K.Lloyd(AT)soton.ac.uk) | 2015-10-16T03:27:39 | oeisdata/seq/A000/A000948.seq | 8cae2eb6cabb318d7558ab7aaea31497 |
A000949 | Number of forests with n nodes and height at most 2. | [
"1",
"1",
"3",
"16",
"101",
"756",
"6607",
"65794",
"733833",
"9046648",
"121961051",
"1782690174",
"28055070397",
"472594822324",
"8479144213191",
"161340195463066",
"3243707386310033",
"68679247688467056",
"1526976223741111987",
"35557878951515668726",
"865217354118762606021"
] | [
"nonn"
] | 33 | 0 | 3 | [
"A000248",
"A000949",
"A000950",
"A000951",
"A052512",
"A052514",
"A210725"
] | [
"M3021",
"N1223"
] | N. J. A. Sloane | 2018-07-03T12:44:37 | oeisdata/seq/A000/A000949.seq | 967938587ffa1e0ca49b3ff7e3a6e405 |
A000950 | Number of forests with n nodes and height at most 3. | [
"1",
"3",
"16",
"125",
"1176",
"12847",
"160504",
"2261289",
"35464816",
"612419291",
"11539360944",
"235469524237",
"5170808565976",
"121535533284999",
"3043254281853496",
"80852247370051793",
"2270951670959226336",
"67221368736302224819",
"2091039845329887687136"
] | [
"nonn"
] | 21 | 1 | 2 | [
"A000248",
"A000949",
"A000950",
"A000951",
"A052512",
"A052514",
"A210725"
] | [
"M3025",
"N1225"
] | N. J. A. Sloane | 2024-05-19T14:03:19 | oeisdata/seq/A000/A000950.seq | 7f45b6e34bdcf58e0af4957b3be3d2a9 |
A000951 | Number of forests with n nodes and height at most 4. | [
"1",
"3",
"16",
"125",
"1296",
"16087",
"229384",
"3687609",
"66025360",
"1303751051",
"28151798544",
"659841763957",
"16681231615816",
"452357366282655",
"13095632549137576",
"403040561722348913",
"13138626717852194976",
"452179922268565180819",
"16381932383826669204640"
] | [
"nonn"
] | 21 | 1 | 2 | [
"A000248",
"A000949",
"A000950",
"A000951",
"A052512",
"A052514",
"A210725"
] | [
"M3026",
"N1226"
] | N. J. A. Sloane | 2024-05-19T14:03:23 | oeisdata/seq/A000/A000951.seq | 48289c7286edb10487cbce6ff3533c17 |
A000952 | Numbers k == 2 (mod 4) that are the orders of conference matrices. | [
"2",
"6",
"10",
"14",
"18",
"26",
"30",
"38",
"42",
"46",
"50",
"54",
"62"
] | [
"nonn",
"hard",
"more",
"nice"
] | 53 | 1 | 1 | [
"A000952",
"A016825",
"A286636"
] | [
"M1574",
"N0615"
] | N. J. A. Sloane | 2023-07-25T23:32:24 | oeisdata/seq/A000/A000952.seq | 442b08592debf4cc43385eef75083e9f |
A000953 | Number of free nonplanar polyenoids with n nodes. | [
"1",
"5",
"24",
"109",
"465",
"1943",
"7827",
"31095",
"121356",
"469235",
"1797376",
"6844290",
"25928036"
] | [
"nonn",
"more"
] | 14 | 7 | 2 | null | null | E. K. Lloyd (E.K.Lloyd(AT)soton.ac.uk) | 2015-10-15T14:30:40 | oeisdata/seq/A000/A000953.seq | a1ba267b770895162b679593431f38d1 |
A000954 | Conjecturally largest even integer which is an unordered sum of two primes in exactly n ways. | [
"2",
"12",
"68",
"128",
"152",
"188",
"332",
"398",
"368",
"488",
"632",
"692",
"626",
"992",
"878",
"908",
"1112",
"998",
"1412",
"1202",
"1448",
"1718",
"1532",
"1604",
"1682",
"2048",
"2252",
"2078",
"2672",
"2642",
"2456",
"2936",
"2504",
"2588",
"2978",
"3092",
"3032",
"3218",
"3272",
"3296",
"3632",
"3548",
"3754",
"4022",
"4058",
"4412"
] | [
"nonn",
"nice"
] | 19 | 0 | 1 | [
"A000954",
"A000974",
"A001172",
"A002375",
"A023036",
"A045917"
] | null | Bill Gosper | 2015-03-12T20:18:18 | oeisdata/seq/A000/A000954.seq | 32d289a810643e1ecede5a84ec6bcb85 |
A000955 | A sequence satisfying (a(2n+1) + 1)^3 = Sum_{k=1..2n+1} a(k)^3. | [
"1",
"6",
"8",
"262",
"2448",
"17997702",
"44082372248",
"5829766629386380698502",
"256989942683351711945337288361248",
"198131491921177194311506308094238133848780474484255622782351242502"
] | [
"nonn"
] | 28 | 1 | 2 | null | [
"M4073",
"N1688"
] | N. J. A. Sloane | 2017-04-01T04:03:30 | oeisdata/seq/A000/A000955.seq | dc36343df87d1156d351dfcb1b6e2718 |
A000956 | A sequence satisfying (a(2n+1) + 1)^3 = Sum_{k=1..2n+1} a(k)^3. | [
"2",
"17",
"40",
"5126",
"211888",
"134691268742",
"28539643139633848",
"2443533691612948322627563638932102",
"69737579558305654640845711279133047105190578109248"
] | [
"nonn"
] | 32 | 1 | 1 | null | [
"M2099",
"N0831"
] | N. J. A. Sloane | 2019-10-22T16:26:48 | oeisdata/seq/A000/A000956.seq | 550a4b33d381924b4d5bc5cf8baffb1c |
A000957 | Fine's sequence (or Fine numbers): number of relations of valence >= 1 on an n-set; also number of ordered rooted trees with n nodes having root of even degree. | [
"0",
"1",
"0",
"1",
"2",
"6",
"18",
"57",
"186",
"622",
"2120",
"7338",
"25724",
"91144",
"325878",
"1174281",
"4260282",
"15548694",
"57048048",
"210295326",
"778483932",
"2892818244",
"10786724388",
"40347919626",
"151355847012",
"569274150156",
"2146336125648",
"8110508473252",
"30711521221376"
] | [
"nonn",
"nice",
"easy"
] | 327 | 0 | 5 | [
"A000012",
"A000045",
"A000108",
"A000957",
"A005043",
"A007317",
"A009766",
"A039598",
"A055395",
"A057078",
"A064306",
"A064310",
"A065600",
"A068875",
"A072547",
"A091867",
"A100754",
"A104597",
"A126093",
"A138413",
"A138414"
] | [
"M1624",
"N0635"
] | N. J. A. Sloane | 2025-02-09T09:45:44 | oeisdata/seq/A000/A000957.seq | 140cfc2a74589c7093dabefac792cfd1 |
A000958 | Number of ordered rooted trees with n edges having root of odd degree. | [
"1",
"1",
"3",
"8",
"24",
"75",
"243",
"808",
"2742",
"9458",
"33062",
"116868",
"417022",
"1500159",
"5434563",
"19808976",
"72596742",
"267343374",
"988779258",
"3671302176",
"13679542632",
"51134644014",
"191703766638",
"720629997168",
"2715610275804",
"10256844598900",
"38822029694628",
"147229736485868"
] | [
"nonn",
"easy"
] | 144 | 1 | 3 | [
"A000108",
"A000957",
"A000958",
"A032357",
"A065602",
"A098747",
"A118973",
"A127539",
"A127541",
"A362563"
] | [
"M2748",
"N1104"
] | N. J. A. Sloane | 2024-12-12T10:56:12 | oeisdata/seq/A000/A000958.seq | 6dc893ed0885085e60b18b5d0e6e7935 |
A000959 | Lucky numbers. | [
"1",
"3",
"7",
"9",
"13",
"15",
"21",
"25",
"31",
"33",
"37",
"43",
"49",
"51",
"63",
"67",
"69",
"73",
"75",
"79",
"87",
"93",
"99",
"105",
"111",
"115",
"127",
"129",
"133",
"135",
"141",
"151",
"159",
"163",
"169",
"171",
"189",
"193",
"195",
"201",
"205",
"211",
"219",
"223",
"231",
"235",
"237",
"241",
"259",
"261",
"267",
"273",
"283",
"285",
"289",
"297",
"303"
] | [
"nonn",
"easy",
"nice",
"core"
] | 218 | 1 | 2 | [
"A000040",
"A000959",
"A003309",
"A031883",
"A032600",
"A039672",
"A045954",
"A050505",
"A054978",
"A109497",
"A137164",
"A137185",
"A145649",
"A219178",
"A249876",
"A254967",
"A255543",
"A255545",
"A255551",
"A255553",
"A258207",
"A264940",
"A265859",
"A362460",
"A362461",
"A362462"
] | [
"M2616",
"N1035"
] | N. J. A. Sloane; entry updated Mar 07 2008 | 2025-02-16T08:32:22 | oeisdata/seq/A000/A000959.seq | 00ef09f53bc977598a40fc3b8b980399 |
A000960 | Flavius Josephus's sieve: Start with the natural numbers; at the k-th sieving step, remove every (k+1)-st term of the sequence remaining after the (k-1)-st sieving step; iterate. | [
"1",
"3",
"7",
"13",
"19",
"27",
"39",
"49",
"63",
"79",
"91",
"109",
"133",
"147",
"181",
"207",
"223",
"253",
"289",
"307",
"349",
"387",
"399",
"459",
"481",
"529",
"567",
"613",
"649",
"709",
"763",
"807",
"843",
"927",
"949",
"1009",
"1093",
"1111",
"1189",
"1261",
"1321",
"1359",
"1471",
"1483",
"1579",
"1693",
"1719",
"1807",
"1899",
"1933",
"2023"
] | [
"nonn",
"easy",
"nice"
] | 109 | 1 | 2 | [
"A000012",
"A000959",
"A000960",
"A002491",
"A003309",
"A003881",
"A056526",
"A056530",
"A056531",
"A099259",
"A100002",
"A100617",
"A100618",
"A112557",
"A112558",
"A113742",
"A113743",
"A113744",
"A113745",
"A113746",
"A113747",
"A113748",
"A113749",
"A119446",
"A119447",
"A190732",
"A278169",
"A278484",
"A278492",
"A278505",
"A278528",
"A278529"
] | [
"M2636",
"N1048"
] | N. J. A. Sloane | 2025-03-03T09:32:40 | oeisdata/seq/A000/A000960.seq | 175b95dcbb622e0f5e7b3b0968480c73 |
A000961 | Powers of primes. Alternatively, 1 and the prime powers (p^k, p prime, k >= 1). | [
"1",
"2",
"3",
"4",
"5",
"7",
"8",
"9",
"11",
"13",
"16",
"17",
"19",
"23",
"25",
"27",
"29",
"31",
"32",
"37",
"41",
"43",
"47",
"49",
"53",
"59",
"61",
"64",
"67",
"71",
"73",
"79",
"81",
"83",
"89",
"97",
"101",
"103",
"107",
"109",
"113",
"121",
"125",
"127",
"128",
"131",
"137",
"139",
"149",
"151",
"157",
"163",
"167",
"169",
"173",
"179",
"181",
"191",
"193",
"197",
"199",
"211",
"223",
"227"
] | [
"nonn",
"easy",
"core",
"nice"
] | 219 | 1 | 2 | [
"A000015",
"A000040",
"A000668",
"A000961",
"A001221",
"A001477",
"A001597",
"A003418",
"A008480",
"A010055",
"A019434",
"A024619",
"A025473",
"A025475",
"A028236",
"A031218",
"A065515",
"A095874",
"A138929",
"A246547",
"A246655"
] | [
"M0517",
"N0185"
] | N. J. A. Sloane | 2025-02-16T08:32:22 | oeisdata/seq/A000/A000961.seq | 8df4159b705eed3ffbf50605ebe33975 |
A000962 | The convergent sequence A_n for the ternary continued fraction (3,1;2,2) of period 2. | [
"1",
"0",
"0",
"1",
"2",
"5",
"15",
"32",
"99",
"210",
"650",
"1379",
"4268",
"9055",
"28025",
"59458",
"184021",
"390420",
"1208340",
"2563621",
"7934342",
"16833545",
"52099395",
"110534372",
"342101079",
"725803590",
"2246343710",
"4765855559",
"14750202128",
"31294112515",
"96854484845",
"205487024518",
"635977131241"
] | [
"nonn",
"easy"
] | 48 | 0 | 5 | [
"A000962",
"A000963",
"A000964"
] | [
"M1473",
"N0582"
] | N. J. A. Sloane | 2022-04-13T13:25:15 | oeisdata/seq/A000/A000962.seq | a02780c9b47958162fa15c74cf35e05b |
A000963 | The convergent sequence B_n for the ternary continued fraction (3,1;2,2) of period 2. | [
"0",
"1",
"0",
"3",
"7",
"16",
"49",
"104",
"322",
"683",
"2114",
"4485",
"13881",
"29450",
"91147",
"193378",
"598500",
"1269781",
"3929940",
"8337783",
"25805227",
"54748516",
"169445269",
"359496044",
"1112631142"
] | [
"nonn",
"cofr",
"easy"
] | 36 | 0 | 4 | [
"A000962",
"A000963",
"A000964"
] | [
"M2660",
"N1062"
] | N. J. A. Sloane | 2022-04-13T13:25:15 | oeisdata/seq/A000/A000963.seq | f072c1a3ae55ef593f921c0806d73d64 |
A000964 | The convergent sequence C_n for the ternary continued fraction (3,1;2,2) of period 2. | [
"0",
"0",
"1",
"1",
"4",
"8",
"25",
"53",
"164",
"348",
"1077",
"2285",
"7072",
"15004",
"46437",
"98521",
"304920",
"646920",
"2002201",
"4247881",
"13147084",
"27892928",
"86327905",
"183153773",
"566856284",
"1202645508",
"3722157357",
"7896950165",
"24440860552",
"51853868404",
"160486408077"
] | [
"nonn",
"easy"
] | 32 | 0 | 5 | [
"A000962",
"A000964"
] | [
"M3343",
"N1345"
] | N. J. A. Sloane | 2019-02-06T02:00:01 | oeisdata/seq/A000/A000964.seq | 0ffc6516b88521132360e44b38d804c1 |
A000965 | Numerators of expansion of e.g.f. sinh(x) / sin(x) (even powers only). | [
"1",
"2",
"4",
"104",
"272",
"3104",
"79808",
"631936",
"1708288",
"7045156352",
"1413417032704",
"6587672324096",
"37378439704576",
"66465881481076736",
"80812831866241024",
"17004045797823707643904",
"55131841948562370265088",
"189924798793194975920128",
"1382061377731043599678963712"
] | [
"nonn",
"easy"
] | 38 | 0 | 2 | [
"A000965",
"A006656",
"A069853"
] | [
"M1307",
"N0501"
] | N. J. A. Sloane | 2022-02-01T08:31:47 | oeisdata/seq/A000/A000965.seq | b04d5c6670f5022673694bfb032960c9 |
A000966 | n! never ends in this many 0's. | [
"5",
"11",
"17",
"23",
"29",
"30",
"36",
"42",
"48",
"54",
"60",
"61",
"67",
"73",
"79",
"85",
"91",
"92",
"98",
"104",
"110",
"116",
"122",
"123",
"129",
"135",
"141",
"147",
"153",
"154",
"155",
"161",
"167",
"173",
"179",
"185",
"186",
"192",
"198",
"204",
"210",
"216",
"217",
"223",
"229",
"235",
"241",
"247",
"248",
"254",
"260",
"266",
"272",
"278",
"279",
"285"
] | [
"nonn",
"base",
"nice"
] | 98 | 1 | 1 | [
"A000142",
"A000966",
"A027868",
"A055938",
"A080066",
"A096346",
"A136767",
"A136774",
"A191610"
] | [
"M3808",
"N1557"
] | N. J. A. Sloane, Robert G. Wilson v | 2022-04-14T03:11:50 | oeisdata/seq/A000/A000966.seq | 9f359adde0e438a276406c7cdf2ca57e |
A000967 | Sum of Fermat coefficients. | [
"1",
"2",
"4",
"8",
"18",
"40",
"91",
"210",
"492",
"1165",
"2786",
"6710",
"16267",
"39650",
"97108",
"238824",
"589521",
"1459960",
"3626213",
"9030450",
"22542396",
"56393792",
"141358274",
"354975429",
"892893120",
"2249412290",
"5674891000",
"14335757256",
"36259245522",
"91815545800"
] | [
"nonn"
] | 33 | 1 | 2 | [
"A000967",
"A143858",
"A258708"
] | [
"M1148",
"N0437"
] | N. J. A. Sloane | 2022-09-08T08:44:28 | oeisdata/seq/A000/A000967.seq | 2873d00a632906cb4315e4a15bf5c7f7 |
A000968 | Sum of odd Fermat coefficients rounded to nearest integer. | [
"1",
"1",
"2",
"4",
"9",
"20",
"46",
"105",
"246",
"583",
"1393",
"3355",
"8133",
"19825",
"48554",
"119412",
"294761",
"729980",
"1813107",
"4515225",
"11271198",
"28196896",
"70679137",
"177487714",
"446446560",
"1124706145",
"2837445500",
"7167878628",
"18129622761",
"45907772900",
"116372614251"
] | [
"nonn"
] | 32 | 1 | 3 | null | [
"M1176",
"N0452"
] | N. J. A. Sloane | 2021-05-09T11:17:24 | oeisdata/seq/A000/A000968.seq | 4cfa71b7d01f373184720f6e2e7ebad3 |
A000969 | Expansion of g.f. (1 + x + 2*x^2)/((1 - x)^2*(1 - x^3)). | [
"1",
"3",
"7",
"12",
"18",
"26",
"35",
"45",
"57",
"70",
"84",
"100",
"117",
"135",
"155",
"176",
"198",
"222",
"247",
"273",
"301",
"330",
"360",
"392",
"425",
"459",
"495",
"532",
"570",
"610",
"651",
"693",
"737",
"782",
"828",
"876",
"925",
"975",
"1027",
"1080",
"1134",
"1190",
"1247",
"1305",
"1365",
"1426",
"1488",
"1552",
"1617",
"1683",
"1751",
"1820",
"1890"
] | [
"nonn",
"easy"
] | 94 | 0 | 2 | [
"A000969",
"A004773",
"A014105",
"A092498",
"A139250",
"A143978",
"A160165",
"A258708"
] | [
"M2630",
"N1042"
] | N. J. A. Sloane | 2023-04-19T09:04:10 | oeisdata/seq/A000/A000969.seq | 28804925a7e5438f8e9352e4718176e9 |
A000970 | Fermat coefficients. | [
"1",
"7",
"25",
"66",
"143",
"273",
"476",
"775",
"1197",
"1771",
"2530",
"3510",
"4750",
"6293",
"8184",
"10472",
"13209",
"16450",
"20254",
"24682",
"29799",
"35673",
"42375",
"49980",
"58565",
"68211",
"79002",
"91025",
"104371",
"119133",
"135408",
"153296",
"172900",
"194327",
"217686",
"243090",
"270655"
] | [
"nonn",
"easy"
] | 61 | 5 | 2 | [
"A000970",
"A258708"
] | [
"M4386",
"N1846"
] | N. J. A. Sloane | 2022-02-28T14:23:18 | oeisdata/seq/A000/A000970.seq | 1f4d6e2ff4a9e46fa25bb6569e41e610 |
A000971 | Fermat coefficients. | [
"1",
"9",
"42",
"132",
"334",
"728",
"1428",
"2584",
"4389",
"7084",
"10963",
"16380",
"23751",
"33563",
"46376",
"62832",
"83657",
"109668",
"141778",
"181001",
"228459",
"285384",
"353127",
"433160",
"527085",
"636636",
"763686",
"910252",
"1078500",
"1270752",
"1489488",
"1737355",
"2017169",
"2331924"
] | [
"nonn",
"easy"
] | 36 | 6 | 2 | [
"A000971",
"A258708"
] | [
"M4623",
"N1975"
] | N. J. A. Sloane | 2016-04-29T01:18:57 | oeisdata/seq/A000/A000971.seq | abb85448a40c16735b8112d714c31d07 |
A000972 | Fermat coefficients. | [
"1",
"12",
"66",
"245",
"715",
"1768",
"3876",
"7752",
"14421",
"25300",
"42287",
"67860",
"105183",
"158224",
"231880",
"332112",
"466089",
"642341",
"870922",
"1163580",
"1533939",
"1997688",
"2572780",
"3279640",
"4141382",
"5184036",
"6436782",
"7932196",
"9706503",
"11799840",
"14256528",
"17125353",
"20459857"
] | [
"nonn",
"easy"
] | 30 | 7 | 2 | [
"A000972",
"A258708"
] | [
"M4847",
"N2072"
] | N. J. A. Sloane | 2017-03-28T14:42:38 | oeisdata/seq/A000/A000972.seq | 37805449345abf2e2f9321a7f388fd9e |
A000973 | Fermat coefficients. | [
"1",
"15",
"99",
"429",
"1430",
"3978",
"9690",
"21318",
"43263",
"82225",
"148005",
"254475",
"420732",
"672452",
"1043460",
"1577532",
"2330445",
"3372291",
"4790071",
"6690585",
"9203634",
"12485550",
"16723070",
"22137570",
"28989675",
"37584261",
"48275865",
"61474519"
] | [
"nonn",
"easy"
] | 59 | 8 | 2 | [
"A000973",
"A053129",
"A258708"
] | [
"M4976",
"N2137"
] | N. J. A. Sloane | 2023-06-24T21:50:34 | oeisdata/seq/A000/A000973.seq | a163730af4ba8b434091d628d1aae24f |
A000974 | Conjecturally the number of even integers the sum of two primes in exactly n ways. | [
"1",
"4",
"9",
"11",
"11",
"16",
"16",
"18",
"20",
"23",
"16",
"29",
"16",
"25",
"27",
"23",
"22",
"25",
"35",
"29",
"26",
"25",
"27",
"27",
"27",
"33",
"28",
"44",
"35",
"21",
"29",
"35",
"38",
"33",
"39",
"37",
"34",
"35",
"31",
"31",
"28",
"41",
"37",
"32",
"44",
"35",
"37",
"41",
"44",
"33",
"37",
"32",
"47",
"39",
"43",
"47",
"33",
"37",
"48",
"41",
"37",
"48",
"34",
"35",
"47",
"36",
"29",
"36",
"46",
"44",
"43",
"38",
"48"
] | [
"nonn"
] | 14 | 0 | 2 | [
"A000954",
"A000974",
"A001172",
"A002375"
] | null | Bill Gosper | 2016-12-25T00:25:10 | oeisdata/seq/A000/A000974.seq | 47b25fd5505ac577a1b89cc7f38ff5c6 |
A000975 | a(2n) = 2*a(2n-1), a(2n+1) = 2*a(2n)+1 (also a(n) is the n-th number without consecutive equal binary digits). | [
"0",
"1",
"2",
"5",
"10",
"21",
"42",
"85",
"170",
"341",
"682",
"1365",
"2730",
"5461",
"10922",
"21845",
"43690",
"87381",
"174762",
"349525",
"699050",
"1398101",
"2796202",
"5592405",
"11184810",
"22369621",
"44739242",
"89478485",
"178956970",
"357913941",
"715827882",
"1431655765",
"2863311530",
"5726623061",
"11453246122"
] | [
"nonn",
"easy",
"nice",
"changed"
] | 522 | 0 | 3 | [
"A000120",
"A000295",
"A000975",
"A001045",
"A001511",
"A002450",
"A003242",
"A003714",
"A003754",
"A005186",
"A005578",
"A007088",
"A013580",
"A014550",
"A015441",
"A020988",
"A022290",
"A026644",
"A027383",
"A033491",
"A035263",
"A043291",
"A051293",
"A053404",
"A056830",
"A059260",
"A067659",
"A070939",
"A077854",
"A079309",
"A104161",
"A107907",
"A107909",
"A119440",
"A127824",
"A130125",
"A135228",
"A153772",
"A155051",
"A164707",
"A179970",
"A231147",
"A261139",
"A264784",
"A295235",
"A300653",
"A319416",
"A325347",
"A359893",
"A359907",
"A361801"
] | null | Mira Bernstein, N. J. A. Sloane, Robert G. Wilson v, Sep 13 1996 | 2025-04-22T07:56:51 | oeisdata/seq/A000/A000975.seq | 24469d9b0224a4465e70982566af0e2a |
A000976 | Period of 1/n! in base 10. | [
"0",
"0",
"1",
"1",
"1",
"1",
"6",
"6",
"18",
"18",
"18",
"54",
"54",
"378",
"1134",
"1134",
"9072",
"81648",
"81648",
"81648",
"1714608",
"18860688",
"18860688",
"56582064",
"56582064",
"735566832",
"19860304464",
"139022131248",
"139022131248",
"417066393744",
"2085331968720",
"2085331968720",
"68815954967760"
] | [
"nonn",
"base"
] | 30 | 1 | 7 | [
"A000142",
"A000976",
"A051626"
] | null | Simon Plouffe | 2023-01-12T01:28:32 | oeisdata/seq/A000/A000976.seq | 84b30240c18598c9e2e8a366e5f462fb |
A000977 | Numbers that are divisible by at least three different primes. | [
"30",
"42",
"60",
"66",
"70",
"78",
"84",
"90",
"102",
"105",
"110",
"114",
"120",
"126",
"130",
"132",
"138",
"140",
"150",
"154",
"156",
"165",
"168",
"170",
"174",
"180",
"182",
"186",
"190",
"195",
"198",
"204",
"210",
"220",
"222",
"228",
"230",
"231",
"234",
"238",
"240",
"246",
"252",
"255",
"258",
"260",
"264",
"266",
"270",
"273",
"276",
"280",
"282",
"285"
] | [
"nonn",
"easy"
] | 46 | 1 | 1 | [
"A000961",
"A000977",
"A007774",
"A033992",
"A033993",
"A051270",
"A070915"
] | null | N. J. A. Sloane | 2024-04-22T08:38:00 | oeisdata/seq/A000/A000977.seq | 387697f62fe41ffd3c9f75d52ae84802 |
A000978 | Wagstaff numbers: numbers k such that (2^k + 1)/3 is prime. | [
"3",
"5",
"7",
"11",
"13",
"17",
"19",
"23",
"31",
"43",
"61",
"79",
"101",
"127",
"167",
"191",
"199",
"313",
"347",
"701",
"1709",
"2617",
"3539",
"5807",
"10501",
"10691",
"11279",
"12391",
"14479",
"42737",
"83339",
"95369",
"117239",
"127031",
"138937",
"141079",
"267017",
"269987",
"374321",
"986191",
"4031399"
] | [
"nonn",
"hard",
"nice",
"more"
] | 132 | 1 | 1 | [
"A000978",
"A000979",
"A001045",
"A010051",
"A065091",
"A107036",
"A124400",
"A124401",
"A127936",
"A127955",
"A127956",
"A127957",
"A127958"
] | [
"M2413",
"N0956"
] | N. J. A. Sloane, Robert G. Wilson v | 2025-02-16T08:32:22 | oeisdata/seq/A000/A000978.seq | 9fe523d31816505dedc898b35259c0c8 |
A000979 | Wagstaff primes: primes of form (2^p + 1)/3. | [
"3",
"11",
"43",
"683",
"2731",
"43691",
"174763",
"2796203",
"715827883",
"2932031007403",
"768614336404564651",
"201487636602438195784363",
"845100400152152934331135470251",
"56713727820156410577229101238628035243",
"62357403192785191176690552862561408838653121833643"
] | [
"nonn"
] | 73 | 1 | 1 | [
"A000978",
"A000979",
"A001045",
"A007583",
"A010051",
"A049883",
"A127962"
] | [
"M2896",
"N1161"
] | N. J. A. Sloane | 2024-08-23T12:17:06 | oeisdata/seq/A000/A000979.seq | ef04f530b7ba5cf4b407c8b98dc1b2b1 |
A000980 | Number of ways of writing 0 as Sum_{k=-n..n} e(k)*k, where e(k) is 0 or 1. | [
"2",
"4",
"8",
"20",
"52",
"152",
"472",
"1520",
"5044",
"17112",
"59008",
"206260",
"729096",
"2601640",
"9358944",
"33904324",
"123580884",
"452902072",
"1667837680",
"6168510256",
"22903260088",
"85338450344",
"318995297200",
"1195901750512",
"4495448217544",
"16940411201280",
"63983233268592"
] | [
"nonn",
"nice"
] | 82 | 0 | 1 | [
"A000975",
"A000980",
"A007318",
"A024718",
"A047653",
"A047997",
"A063865",
"A070925",
"A079309",
"A084239",
"A133406",
"A141000",
"A212352",
"A327475",
"A327481",
"A359893",
"A362046"
] | [
"M1155",
"N0439"
] | N. J. A. Sloane | 2023-10-28T13:09:12 | oeisdata/seq/A000/A000980.seq | ef03d1cefb38b1820e8c5d697fe2ce6d |
A000981 | Numbers beginning with letter 'n' in English. | [
"9",
"19",
"90",
"91",
"92",
"93",
"94",
"95",
"96",
"97",
"98",
"99",
"900",
"901",
"902",
"903",
"904",
"905",
"906",
"907",
"908",
"909",
"910",
"911",
"912",
"913",
"914",
"915",
"916",
"917",
"918",
"919",
"920",
"921",
"922",
"923",
"924",
"925",
"926",
"927",
"928",
"929",
"930"
] | [
"word",
"nonn"
] | 12 | 1 | 1 | [
"A000865",
"A000867",
"A000870",
"A000873",
"A000981",
"A006092",
"A125299"
] | null | N. J. A. Sloane | 2017-04-01T00:45:59 | oeisdata/seq/A000/A000981.seq | 4cb23ba70fe1bf5140f1fab42be9dff5 |
A000982 | a(n) = ceiling(n^2/2). | [
"0",
"1",
"2",
"5",
"8",
"13",
"18",
"25",
"32",
"41",
"50",
"61",
"72",
"85",
"98",
"113",
"128",
"145",
"162",
"181",
"200",
"221",
"242",
"265",
"288",
"313",
"338",
"365",
"392",
"421",
"450",
"481",
"512",
"545",
"578",
"613",
"648",
"685",
"722",
"761",
"800",
"841",
"882",
"925",
"968",
"1013",
"1058",
"1105",
"1152",
"1201",
"1250",
"1301",
"1352",
"1405"
] | [
"nonn",
"easy"
] | 324 | 0 | 3 | [
"A000096",
"A000217",
"A000982",
"A001105",
"A001477",
"A001844",
"A002061",
"A004526",
"A005843",
"A007590",
"A008794",
"A037270",
"A081352",
"A109613",
"A110654",
"A116940",
"A132188",
"A134444",
"A158946",
"A168380",
"A195040",
"A357501",
"A362931"
] | [
"M1348",
"N0517"
] | N. J. A. Sloane | 2025-04-07T05:02:00 | oeisdata/seq/A000/A000982.seq | df6d0405b9bdf0612110b34a8e6dc424 |
A000983 | Size of minimal binary covering code of length n and covering radius 1. | [
"1",
"2",
"2",
"4",
"7",
"12",
"16",
"32",
"62"
] | [
"nonn",
"hard",
"more",
"nice"
] | 83 | 1 | 2 | [
"A000983",
"A029866",
"A060438"
] | [
"M0329",
"N0124"
] | N. J. A. Sloane | 2025-02-16T08:32:22 | oeisdata/seq/A000/A000983.seq | 6af2ff248d33e68fcbae9751ce77e956 |
A000984 | Central binomial coefficients: binomial(2*n,n) = (2*n)!/(n!)^2. | [
"1",
"2",
"6",
"20",
"70",
"252",
"924",
"3432",
"12870",
"48620",
"184756",
"705432",
"2704156",
"10400600",
"40116600",
"155117520",
"601080390",
"2333606220",
"9075135300",
"35345263800",
"137846528820",
"538257874440",
"2104098963720",
"8233430727600",
"32247603683100",
"126410606437752",
"495918532948104",
"1946939425648112"
] | [
"nonn",
"easy",
"core",
"nice",
"walk",
"frac"
] | 1,079 | 0 | 2 | [
"A000079",
"A000108",
"A000172",
"A000346",
"A000984",
"A001316",
"A001405",
"A001700",
"A001791",
"A002144",
"A002420",
"A002457",
"A002893",
"A002895",
"A005258",
"A005259",
"A005260",
"A005261",
"A006077",
"A008459",
"A008549",
"A025565",
"A030662",
"A032443",
"A036917",
"A046521",
"A051924",
"A056040",
"A059481",
"A063007",
"A069865",
"A071976",
"A073016",
"A081085",
"A081696",
"A093388",
"A097805",
"A098616",
"A125143",
"A126869",
"A135091",
"A143003",
"A143007",
"A143413",
"A143414",
"A143415",
"A143583",
"A152229",
"A158815",
"A182400",
"A182421",
"A182422",
"A182446",
"A182447",
"A183204",
"A205946",
"A214262",
"A214377",
"A219692",
"A226078",
"A226302",
"A226535",
"A227216",
"A227454",
"A229111",
"A258290",
"A260667",
"A260832",
"A261009",
"A261130",
"A262177",
"A264541",
"A264542",
"A279619",
"A290575",
"A290576",
"A342294",
"A342295",
"A356637"
] | [
"M1645",
"N0643"
] | N. J. A. Sloane | 2025-04-01T04:13:40 | oeisdata/seq/A000/A000984.seq | 318f269cdae044f6b321bd8c115a2120 |
A000985 | Number of n X n symmetric matrices with nonnegative entries and all row sums 2. | [
"1",
"1",
"3",
"11",
"56",
"348",
"2578",
"22054",
"213798",
"2313638",
"27627434",
"360646314",
"5107177312",
"77954299144",
"1275489929604",
"22265845018412",
"412989204564572",
"8109686585668956",
"168051656468233972",
"3664479286118269972",
"83868072451846938336",
"2009964340465840802576"
] | [
"nonn",
"nice",
"easy"
] | 44 | 0 | 3 | [
"A000985",
"A000986"
] | [
"M2907",
"N1168"
] | N. J. A. Sloane | 2025-01-13T11:24:27 | oeisdata/seq/A000/A000985.seq | 8b79fc473446bbc017a692a9f8e1c877 |
A000986 | Number of n X n symmetric matrices with (0,1) entries and all row sums 2. | [
"1",
"0",
"1",
"4",
"18",
"112",
"820",
"6912",
"66178",
"708256",
"8372754",
"108306280",
"1521077404",
"23041655136",
"374385141832",
"6493515450688",
"119724090206940",
"2337913445039488",
"48195668439235612",
"1045828865817825264",
"23826258064972682776",
"568556266922455167040"
] | [
"nonn",
"nice",
"easy",
"changed"
] | 63 | 0 | 4 | [
"A000985",
"A000986",
"A001205"
] | [
"M3548",
"N1437"
] | N. J. A. Sloane | 2025-04-14T07:38:11 | oeisdata/seq/A000/A000986.seq | b6ecffa3ed4b44b0e2b87534cb8ee031 |
A000987 | Number of stochastic matrices of integers. | [
"0",
"1",
"1",
"2",
"7",
"32",
"184",
"1268",
"10186",
"93356",
"960646",
"10959452",
"137221954",
"1870087808",
"27548231008",
"436081302248",
"7380628161076",
"132975267434552",
"2540593483517404",
"51299775805464824",
"1091447620966600804",
"24401984084483685248",
"571907754141520643296"
] | [
"nonn"
] | 32 | 0 | 4 | null | [
"M1793",
"N0707"
] | N. J. A. Sloane | 2017-05-24T08:34:15 | oeisdata/seq/A000/A000987.seq | 05482e01a076ea55500bd7a78b7c5986 |
A000988 | Number of one-sided polyominoes with n cells. | [
"1",
"1",
"1",
"2",
"7",
"18",
"60",
"196",
"704",
"2500",
"9189",
"33896",
"126759",
"476270",
"1802312",
"6849777",
"26152418",
"100203194",
"385221143",
"1485200848",
"5741256764",
"22245940545",
"86383382827",
"336093325058",
"1309998125640",
"5114451441106",
"19998172734786",
"78306011677182",
"307022182222506",
"1205243866707468",
"4736694001644862"
] | [
"nonn"
] | 72 | 0 | 4 | [
"A000105",
"A000988",
"A001168",
"A006758",
"A030227",
"A030228",
"A195738"
] | [
"M1749",
"N0693"
] | N. J. A. Sloane, hugh(AT)mimosa.com (D. Hugh Redelmeier) | 2025-02-16T08:32:22 | oeisdata/seq/A000/A000988.seq | 66e5b99fd02dd66cf14c6284c7809bdc |
A000989 | 3-adic valuation of binomial(2*n, n): largest k such that 3^k divides binomial(2*n, n). | [
"0",
"0",
"1",
"0",
"0",
"2",
"1",
"1",
"2",
"0",
"0",
"1",
"0",
"0",
"3",
"2",
"2",
"3",
"1",
"1",
"2",
"1",
"1",
"3",
"2",
"2",
"3",
"0",
"0",
"1",
"0",
"0",
"2",
"1",
"1",
"2",
"0",
"0",
"1",
"0",
"0",
"4",
"3",
"3",
"4",
"2",
"2",
"3",
"2",
"2",
"4",
"3",
"3",
"4",
"1",
"1",
"2",
"1",
"1",
"3",
"2",
"2",
"3",
"1",
"1",
"2",
"1",
"1",
"4",
"3",
"3",
"4",
"2",
"2",
"3",
"2",
"2",
"4",
"3",
"3"
] | [
"nonn",
"easy"
] | 51 | 0 | 6 | [
"A000984",
"A000989",
"A005836",
"A007949",
"A053735"
] | null | N. J. A. Sloane, R. K. Guy | 2021-02-12T04:03:21 | oeisdata/seq/A000/A000989.seq | 3e45f1a6671ee8320d87da31c3d7cc44 |
A000990 | Number of plane partitions of n with at most two rows. | [
"1",
"1",
"3",
"5",
"10",
"16",
"29",
"45",
"75",
"115",
"181",
"271",
"413",
"605",
"895",
"1291",
"1866",
"2648",
"3760",
"5260",
"7352",
"10160",
"14008",
"19140",
"26085",
"35277",
"47575",
"63753",
"85175",
"113175",
"149938",
"197686",
"259891",
"340225",
"444135",
"577593",
"749131",
"968281",
"1248320",
"1604340",
"2056809",
"2629357",
"3353404"
] | [
"nonn",
"easy"
] | 85 | 0 | 3 | [
"A000041",
"A000070",
"A000712",
"A000990",
"A000991",
"A001452",
"A002799",
"A008619",
"A147767",
"A225196",
"A225197",
"A225198",
"A225199",
"A242641"
] | [
"M2462",
"N0978"
] | N. J. A. Sloane | 2025-04-07T22:56:16 | oeisdata/seq/A000/A000990.seq | 7deec2ef7ac9692c04e0bb69b8ec256f |
A000991 | Number of 3-line partitions of n. | [
"1",
"1",
"3",
"6",
"12",
"21",
"40",
"67",
"117",
"193",
"319",
"510",
"818",
"1274",
"1983",
"3032",
"4610",
"6915",
"10324",
"15235",
"22371",
"32554",
"47119",
"67689",
"96763",
"137404",
"194211",
"272939",
"381872",
"531576",
"736923",
"1016904",
"1397853",
"1913561",
"2610023",
"3546507",
"4802694",
"6481101",
"8718309",
"11689929",
"15627591",
"20828892"
] | [
"nonn"
] | 59 | 0 | 3 | [
"A000041",
"A000990",
"A000991",
"A001452",
"A002799",
"A225196",
"A225197",
"A225198",
"A225199",
"A242641"
] | [
"M2554",
"N1011"
] | N. J. A. Sloane | 2023-10-27T18:03:15 | oeisdata/seq/A000/A000991.seq | 2ef32a7df7cff014116b4fbf817f08a9 |
A000992 | "Half-Catalan numbers": a(n) = Sum_{k=1..floor(n/2)} a(k)*a(n-k) with a(1) = 1. | [
"1",
"1",
"1",
"2",
"3",
"6",
"11",
"24",
"47",
"103",
"214",
"481",
"1030",
"2337",
"5131",
"11813",
"26329",
"60958",
"137821",
"321690",
"734428",
"1721998",
"3966556",
"9352353",
"21683445",
"51296030",
"119663812",
"284198136",
"666132304",
"1586230523",
"3734594241",
"8919845275",
"21075282588",
"50441436842"
] | [
"nonn",
"easy",
"nice"
] | 93 | 1 | 4 | [
"A000108",
"A000992",
"A001190",
"A093637",
"A124973",
"A248748"
] | [
"M0793",
"N0300"
] | N. J. A. Sloane | 2024-11-04T11:12:41 | oeisdata/seq/A000/A000992.seq | cf30324eab4134e0a331836a8e3e6cbc |
A000993 | Number of distinct quadratic residues mod 10^n; also number of distinct n-digit endings of base-10 squares. | [
"1",
"6",
"22",
"159",
"1044",
"9121",
"78132",
"748719",
"7161484",
"70800861",
"699869892",
"6978353179",
"69580078524",
"695292156201",
"6947835288052",
"69465637212039",
"694529215501164",
"6944974263529141",
"69446563720728612",
"694457689921141299",
"6944497426351013404"
] | [
"nonn",
"easy",
"nice",
"base"
] | 63 | 0 | 2 | [
"A000993",
"A023105",
"A036688",
"A039300",
"A039306",
"A075821",
"A075823"
] | [
"M4155",
"N1727"
] | N. J. A. Sloane | 2025-03-15T09:41:38 | oeisdata/seq/A000/A000993.seq | ed39bd2ea4c7aab679feef9aaf9ab6af |
A000994 | Shifts 2 places left under binomial transform. | [
"1",
"0",
"1",
"1",
"2",
"5",
"13",
"36",
"109",
"359",
"1266",
"4731",
"18657",
"77464",
"337681",
"1540381",
"7330418",
"36301105",
"186688845",
"995293580",
"5491595645",
"31310124067",
"184199228226",
"1116717966103",
"6968515690273",
"44710457783760",
"294655920067105",
"1992750830574681",
"13817968813639426"
] | [
"nonn",
"easy",
"nice",
"eigen"
] | 61 | 0 | 5 | [
"A000994",
"A000995",
"A007318",
"A007476",
"A051139",
"A051140",
"A086880",
"A088022",
"A143983"
] | [
"M1446",
"N0572"
] | N. J. A. Sloane | 2023-07-03T18:11:04 | oeisdata/seq/A000/A000994.seq | 5b192281a1ed1fcf65052fef154d2567 |
A000995 | Shifts left two terms under the binomial transform. | [
"0",
"1",
"0",
"1",
"2",
"4",
"10",
"29",
"90",
"295",
"1030",
"3838",
"15168",
"63117",
"275252",
"1254801",
"5968046",
"29551768",
"152005634",
"810518729",
"4472244574",
"25497104007",
"149993156234",
"909326652914",
"5674422994544",
"36408092349897",
"239942657880360"
] | [
"nonn",
"eigen",
"easy",
"nice"
] | 70 | 0 | 5 | [
"A000994",
"A000995",
"A007318",
"A051139",
"A051140",
"A137854"
] | [
"M1228",
"N0471"
] | N. J. A. Sloane | 2019-05-02T08:50:18 | oeisdata/seq/A000/A000995.seq | efbfb2a077036388eb220816fb805259 |
A000996 | Shifts 3 places left under binomial transform. | [
"1",
"0",
"0",
"1",
"1",
"1",
"2",
"6",
"17",
"44",
"112",
"304",
"918",
"3040",
"10623",
"38161",
"140074",
"528594",
"2068751",
"8436893",
"35813251",
"157448068",
"713084042",
"3315414747",
"15805117878",
"77273097114",
"387692392570",
"1996280632656",
"10542604575130",
"57034787751655",
"315649657181821"
] | [
"nonn",
"eigen"
] | 38 | 0 | 7 | [
"A000996",
"A143983"
] | [
"M1618",
"N0632"
] | N. J. A. Sloane | 2020-08-09T17:13:16 | oeisdata/seq/A000/A000996.seq | fe34401d11ab3174c7af9215b06e8533 |
A000997 | From a differential equation. | [
"0",
"1",
"0",
"0",
"1",
"2",
"3",
"5",
"12",
"36",
"110",
"326",
"963",
"2964",
"9797",
"34818",
"130585",
"506996",
"2018454",
"8238737",
"34627390",
"150485325",
"677033911",
"3147372610",
"15066340824",
"74025698886",
"372557932434",
"1919196902205",
"10119758506626",
"54627382038761",
"301832813494746"
] | [
"nonn",
"eigen"
] | 27 | 0 | 6 | [
"A000995",
"A000997"
] | [
"M0739",
"N0277"
] | N. J. A. Sloane | 2019-10-23T12:19:07 | oeisdata/seq/A000/A000997.seq | be64036d387b3dfba5d35b96be872ad3 |
A000998 | From a differential equation. | [
"1",
"3",
"6",
"11",
"24",
"69",
"227",
"753",
"2451",
"8004",
"27138",
"97806",
"375313",
"1511868",
"6292884",
"26826701",
"116994453",
"523646202",
"2414394601",
"11487130362",
"56341183365",
"284110648983",
"1468690344087",
"7766823788295",
"41976012524088",
"231812530642644",
"1308325741771908"
] | [
"nonn",
"eigen"
] | 25 | 0 | 2 | null | [
"M2549",
"N1009"
] | N. J. A. Sloane | 2020-10-27T08:48:08 | oeisdata/seq/A000/A000998.seq | e81fd28dc47d16f0234a51e0ee275e4f |
A000999 | 5-adic valuation of binomial(2*n,n): largest k such that 5^k divides binomial(2*n, n). | [
"0",
"0",
"0",
"1",
"1",
"0",
"0",
"0",
"1",
"1",
"0",
"0",
"0",
"2",
"2",
"1",
"1",
"1",
"2",
"2",
"1",
"1",
"1",
"2",
"2",
"0",
"0",
"0",
"1",
"1",
"0",
"0",
"0",
"1",
"1",
"0",
"0",
"0",
"2",
"2",
"1",
"1",
"1",
"2",
"2",
"1",
"1",
"1",
"2",
"2",
"0",
"0",
"0",
"1",
"1",
"0",
"0",
"0",
"1",
"1",
"0",
"0",
"0",
"3",
"3",
"2",
"2",
"2",
"3",
"3",
"2",
"2",
"2",
"3",
"3",
"1",
"1",
"1",
"2",
"2",
"1",
"1",
"1",
"2",
"2",
"1",
"1"
] | [
"nonn",
"easy"
] | 23 | 0 | 14 | [
"A000984",
"A000989",
"A000999",
"A053824",
"A112765"
] | null | N. J. A. Sloane, R. K. Guy | 2023-03-07T02:35:27 | oeisdata/seq/A000/A000999.seq | 20f42a4c90c120a2fe1255abc7f8ef6d |
A001000 | a(n) = least m such that if a/b < c/d where a,b,c,d are integers in [0,n], then a/b < k/m < c/d for some integer k. | [
"2",
"3",
"5",
"7",
"13",
"17",
"26",
"31",
"43",
"57",
"65",
"82",
"101",
"111",
"133",
"157",
"183",
"197",
"226",
"257",
"290",
"307",
"343",
"381",
"421",
"463",
"485",
"530",
"577",
"626",
"677",
"703",
"757",
"813",
"871",
"931",
"993",
"1025",
"1090",
"1157",
"1226",
"1297",
"1370",
"1407",
"1483",
"1561",
"1641",
"1723",
"1807",
"1893",
"1937",
"2026",
"2117"
] | [
"nonn",
"nice"
] | 29 | 1 | 1 | [
"A001000",
"A071111"
] | null | Clark Kimberling | 2016-12-26T01:50:01 | oeisdata/seq/A001/A001000.seq | 2d9d993d4f27a80abd2e736dcc32bcc6 |
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