cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-4 of 4 results.

A056520 a(n) = (n + 2)*(2*n^2 - n + 3)/6.

Original entry on oeis.org

1, 2, 6, 15, 31, 56, 92, 141, 205, 286, 386, 507, 651, 820, 1016, 1241, 1497, 1786, 2110, 2471, 2871, 3312, 3796, 4325, 4901, 5526, 6202, 6931, 7715, 8556, 9456, 10417, 11441, 12530, 13686, 14911, 16207, 17576, 19020, 20541, 22141, 23822
Offset: 0

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Author

N. J. A. Sloane, Laura Kasavan (maui12129(AT)cswebmail.com), Aug 26 2000

Keywords

Comments

Hankel transform of A030238. - Paul Barry, Oct 16 2007
Equals (1, 2, 3, 4, 5, ...) convolved with (1, 0, 3, 5, 7, 9, ...). - Gary W. Adamson, Jul 31 2010
a(n) equals n!^2 times the determinant of the n X n matrix whose (i,j)-entry is 1 + KroneckerDelta[i, j] (-1 + (1 + i^2)/i^2). - John M. Campbell, May 20 2011
Positions of ones in A253903 (with offset 1). - Harvey P. Dale, Mar 05 2015

Crossrefs

Programs

Formula

a(n) = a(n-1) + n^2.
a(n) = A000330(n) + 1.
G.f.: (1 - 2*x + 4*x^2 - x^3)/(1 - x)^4. - Paul Barry, Apr 14 2010
Let b(0) = b(1) = 1, b(n) = max(b(n-1) + (n - 1)^2, b(n-2) + (n - 2)^2) for n >= 2; then a(n) = b(n+1). - Yalcin Aktar, Jul 28 2011

A153058 a(0)=4; a(n)=n^2+a(n-1) for n>0.

Original entry on oeis.org

4, 5, 9, 18, 34, 59, 95, 144, 208, 289, 389, 510, 654, 823, 1019, 1244, 1500, 1789, 2113, 2474, 2874, 3315, 3799, 4328, 4904, 5529, 6205, 6934, 7718, 8559, 9459, 10420, 11444, 12533, 13689, 14914, 16210, 17579, 19023, 20544, 22144, 23825, 25589
Offset: 0

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Author

Keywords

Crossrefs

Programs

  • Mathematica
    a=4;lst={};Do[a=n^2+a;AppendTo[lst,a],{n,0,5!}];lst
    RecurrenceTable[{a[0]==4,a[n]==n^2+a[n-1]},a,{n,50}] (* Harvey P. Dale, Apr 27 2012 *)

Formula

G.f.: (4-11x+13x^2-4x^3)/(1-x)^4. a(n)=4+A000330(n). - R. J. Mathar, Jan 17 2009

Extensions

Added indices to definition and corrected offset. - R. J. Mathar, Jan 17 2009

A153056 a(0)=2, a(n) = n^2+a(n-1).

Original entry on oeis.org

2, 3, 7, 16, 32, 57, 93, 142, 206, 287, 387, 508, 652, 821, 1017, 1242, 1498, 1787, 2111, 2472, 2872, 3313, 3797, 4326, 4902, 5527, 6203, 6932, 7716, 8557, 9457, 10418, 11442, 12531, 13687, 14912, 16208, 17577, 19021, 20542, 22142, 23823, 25587
Offset: 0

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Author

Keywords

Crossrefs

Programs

  • Mathematica
    a=2;lst={};Do[a=n^2+a;AppendTo[lst,a],{n,0,5!}];lst
    nxt[{n_,a_}]:={n+1,(n+1)^2+a}; NestList[nxt,{0,2},50][[;;,2]] (* or *) LinearRecurrence[{4,-6,4,-1},{2,3,7,16},50] (* Harvey P. Dale, Sep 05 2023 *)
  • PARI
    a(n) = n*(n+1)*(2*n+1)/6 + 2; \\ Altug Alkan, Apr 30 2018

Formula

G.f.: (2-5x+7x^2-2x^3)/(1-x)^4. a(n)=2+n(1+2n^2+3n)/6 = 2+A000330(n). - R. J. Mathar, Jan 08 2009

A153057 a(0)=3; a(n) = n^2 + a(n-1) for n>0.

Original entry on oeis.org

3, 4, 8, 17, 33, 58, 94, 143, 207, 288, 388, 509, 653, 822, 1018, 1243, 1499, 1788, 2112, 2473, 2873, 3314, 3798, 4327, 4903, 5528, 6204, 6933, 7717, 8558, 9458, 10419, 11443, 12532, 13688, 14913, 16209, 17578, 19022, 20543, 22143, 23824, 25588
Offset: 0

Views

Author

Keywords

Crossrefs

Programs

  • Magma
    I:=[3,4,8,17]; [n le 4 select I[n] else 4*Self(n-1)-6*Self(n-2)+4*Self(n-3)-Self(n-4): n in [1..60]]; // Vincenzo Librandi, May 09 2017
  • Mathematica
    a=3;lst={};Do[a=n^2+a;AppendTo[lst,a],{n,0,5!}];lst
    CoefficientList[Series[(3 - 8 x + 10 x^2 - 3 x^3) / (1 - x)^4, {x, 0, 50}], x] (* Vincenzo Librandi, May 09 2017 *)

Formula

From R. J. Mathar, Jan 17 2009: (Start)
G.f.: (3-8*x + 10*x^2 - 3*x^3)/(1 - x)^4.
a(n) = 3+A000330(n). (End)
a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4). - Vincenzo Librandi, May 09 2017

Extensions

Added indices to definition. Corrected offset R. J. Mathar, Jan 17 2009
Showing 1-4 of 4 results.