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 1-7 of 7 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

A028300 a(1) = 1; thereafter a(n+1) = a(n)^2 + n.

Original entry on oeis.org

1, 2, 6, 39, 1525, 2325630, 5408554896906, 29252466072845872288372843, 855706771342998810018458679815602502067088579902657
Offset: 1

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Author

A.R. Fink (fink(AT)cadvision.com)

Keywords

Examples

			a(3) = a(2)^2+2 = 4+2 = 6.
		

Crossrefs

Programs

  • Magma
    [n le 1 select 1 else Self(n-1)^2 +n-1: n in [1..14]]; // G. C. Greubel, Jan 03 2024
    
  • Mathematica
    RecurrenceTable[{a[1]==1, a[n+1]==a[n]^2 + n}, a, {n,10}] (* Vaclav Kotesovec, Dec 18 2014 *)
  • SageMath
    def a(n): return 1 if n==1 else a(n-1)^2 + n-1 # a = A028300
    [a(n) for n in range(1,15)] # G. C. Greubel, Jan 03 2024

Formula

a(n) ~ c^(2^n), where c = 1.2574108318043003098123273077302829405940294\ 604970047023808427877694426442... . - Vaclav Kotesovec, Dec 18 2014

A098152 a(n) = a(n-1)^2 + n, with a(0)=0.

Original entry on oeis.org

0, 1, 3, 12, 148, 21909, 480004287, 230404115538378376, 53086056457022411804685755744397384, 2818129390158170901506703075470572449397357853477615482257305306043465
Offset: 0

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Author

Henry Bottomley, Oct 25 2004

Keywords

Examples

			a(4) = a(3)^2 + 4 =12^2 + 4 = 148.
		

Crossrefs

Programs

Formula

For n>0, a(n) = floor(1.366609561487624975914833969579996...^(2^n)) = floor(A028300(n)^0.68178667449368682115305109818...) = ceiling(A003095(n)^1.53346965582393874689368175542252...).

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

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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

A179904 a(n) = A056520(n)+1 for n>0, a(0)=1.

Original entry on oeis.org

1, 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

Views

Author

Gary W. Adamson, Jul 31 2010

Keywords

Comments

Original name: (1,3,5,7,9,..) = A005408 convolved with (1,0,2,3,4,..) = 1 followed by A087156.

Examples

			a(3) = 16 = 1 + A056520(3) = (1 + 15).
a(4) = 32 = (9, 7, 5, 3, 1) dot (1, 0, 2, 3, 4) = (9 + 0 + 10 + 9 + 4).
		

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{4,-6,4,-1},{1,3,7,16,32},50] (* Harvey P. Dale, Apr 25 2020 *)

Formula

From Bruno Berselli, Aug 26 2011: (Start)
G.f.: (1 + x)*(1 - 2*x + 3*x^2 - x^3)/(1 - x)^4.
a(n) = (1/6)*(2*n^3 + 3*n^2 + n + 12) for n>0, a(0)=1. (End)
a(n) = A153056(n) for n > 0. - Georg Fischer, Oct 24 2018

Extensions

More terms and a(20) added by Bruno Berselli, Aug 26 2011

A153062 a(0)=1, a(n)=a(n-1)^2-n^2.

Original entry on oeis.org

1, 0, -4, 7, 33, 1064, 1132060, 1281559843551, 1642395632602463596289537, 2697463413991646582332856337058890220473935674288, 7276308869823469318922107258255539214217660183827400648026742290333726278585952350082821224306844
Offset: 0

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Author

Keywords

Crossrefs

Programs

  • Mathematica
    a=1;lst={};Do[a=a^2-n^2;AppendTo[lst,a],{n,0,12}];lst
    RecurrenceTable[{a[0]==1, a[n]==a[n-1]^2-n^2}, a, {n, 0, 10}] (* Vaclav Kotesovec, Dec 18 2014 *)

Formula

a(n) ~ c^(2^n), where c = 1.24334516566159378905145559484975509773481252881469517052010008004602693351819... . - Vaclav Kotesovec, Dec 18 2014
Showing 1-7 of 7 results.