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 1-10 of 32 results. Next

A027107 a(n) = Sum_{k=0..2n} (k+1) * A027082(n, 2n-k).

Original entry on oeis.org

1, 6, 20, 62, 188, 566, 1700, 5102, 15308, 45926, 137780, 413342, 1240028, 3720086, 11160260, 33480782, 100442348, 301327046, 903981140, 2711943422, 8135830268, 24407490806, 73222472420, 219667417262, 659002251788
Offset: 0

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Formula

For n>0, a(n) = 7*3^(n-1) - 1.
G.f.: (1+2*x-x^2)/(1-4*x+3*x^2). [Bruno Berselli, Mar 25 2013]
a(n) = 2*A237930(n-1), n>0. - R. J. Mathar, Jun 24 2020

A027083 a(n) = A027082(n, n+2).

Original entry on oeis.org

2, 6, 14, 28, 54, 102, 190, 352, 650, 1198, 2206, 4060, 7470, 13742, 25278, 46496, 85522, 157302, 289326, 532156, 978790, 1800278, 3311230, 6090304, 11201818, 20603358, 37895486, 69700668, 128199518, 235795678, 433695870
Offset: 2

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Programs

  • Mathematica
    LinearRecurrence[{2, 0, 0, -1}, {2, 6, 14, 28}, 50] (* Paolo Xausa, Sep 16 2024 *)

Formula

G.f.: (2x^2(1+x+x^2))/((1-x)(1-x-x^2-x^3)). Cf. A008937.
a(n) = A027024(n) + 1.
a(n) = A000213(n+3) -3. - R. J. Mathar, Jun 24 2020

A027086 a(n) = A027082(n, n+4).

Original entry on oeis.org

11, 41, 108, 246, 517, 1035, 2010, 3828, 7199, 13429, 24920, 46090, 85065, 156791, 288758, 531528, 978099, 1799521, 3310404, 6089406, 11200845, 20602307, 37894354, 69699452, 128198215, 235794285, 433694384, 797689490, 1467180945, 2698567791, 4963441390
Offset: 4

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  • Magma
    I:=[11,41,108,246,517,1035]; [n le 6 select I[n] else 4*Self(n-1)-5*Self(n-2)+2*Self(n-3)-Self(n-4)+2*Self(n-5)-Self(n-6): n in [1..40]]; // Vincenzo Librandi, Feb 20 2016
  • Mathematica
    LinearRecurrence[{4, -5, 2, -1, 2, -1}, {11, 41, 108, 246, 517, 1035}, 35] (* Vincenzo Librandi, Feb 20 2016 *)
  • PARI
    Vec(x^4*(11-3*x-x^2-3*x^3+2*x^4)/((1-x)^3*(1-x-x^2-x^3)) + O(x^40)) \\ Colin Barker, Feb 20 2016
    

Formula

a(n) = A027026(n) + (n+1)(n+2)/2 - 3.
From Colin Barker, Feb 20 2016: (Start)
a(n) = 4*a(n-1)-5*a(n-2)+2*a(n-3)-a(n-4)+2*a(n-5)-a(n-6) for n>9.
G.f.: x^4*(11-3*x-x^2-3*x^3+2*x^4) / ((1-x)^3*(1-x-x^2-x^3)).
(End)
a(n) = A000213(n+4) -4 -3*n*(n+3)/2. - R. J. Mathar, Jun 24 2020

A027098 T(n,n) + T(n,n+1) + ... + T(n,2n), T given by A027082.

Original entry on oeis.org

1, 2, 6, 19, 55, 161, 469, 1362, 3954, 11483, 33379, 97146, 283114, 826214, 2414366, 7064217, 20693797, 60686847, 178152055, 523473326, 1539479414, 4531059224, 13345835288, 39335816471, 116012701523, 342356498884
Offset: 0

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A027085 a(n) = A027082(n, n+3).

Original entry on oeis.org

5, 16, 39, 84, 169, 328, 623, 1168, 2173, 4024, 7431, 13700, 25233, 46448, 85471, 157248, 289269, 532096, 978727, 1800212, 3311161, 6090232, 11201743, 20603280, 37895405, 69700584, 128199431, 235795588, 433695777, 797690976
Offset: 0

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Programs

  • Mathematica
    CoefficientList[Series[-((-x^3+x^2+x+5)/((x-1)^2 (x^3+x^2+x-1))),{x,0,30}],x] (* Harvey P. Dale, May 15 2013 *)

Formula

G.f.: (x^3-x^2-x-5)/((x-1)^2(x^3+x^2+x-1)). - Harvey P. Dale, May 15 2013
a(n) = A027025(n) + n + 1.
a(n) = A000213(n+6) -3*(n+4). - R. J. Mathar, Jun 24 2020

A027087 a(n) = A027082(n, 2n).

Original entry on oeis.org

1, 1, 2, 5, 11, 27, 68, 175, 458, 1215, 3258, 8815, 24031, 65937, 181936, 504473, 1404879, 3927495, 11017802, 31004871, 87497297, 247559933, 702089528, 1995483853, 5682959332, 16214622573, 46343364290, 132667706857, 380358924209
Offset: 0

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Crossrefs

Cf. A027082.

Formula

Conjecture: D-finite with recurrence +3*n*a(n) +3*(-5*n+3)*a(n-1) +(7*n-4)*a(n-2) +(25*n-67)*a(n-3) +(17*n-44)*a(n-4) +(19*n-97)*a(n-5) +(5*n-32)*a(n-6) +3*(n-7)*a(n-7)=0. - R. J. Mathar, Jun 24 2020

A027088 a(n) = A027082(n, 2n-1).

Original entry on oeis.org

1, 3, 6, 16, 41, 107, 283, 757, 2043, 5557, 15216, 41906, 115999, 322537, 900406, 2522616, 7090307, 19987069, 56492426, 160062636, 454529595, 1293394325, 3687475479, 10531663241, 30128741717, 86324342567, 247691217352
Offset: 1

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Cf. A027082.

Formula

Conjecture: D-finite with recurrence 3*(n+1)*(18*n-85)*a(n) +(292*n^2-1316*n-255)*a(n-1) +(-218*n^2+1213*n-1056)*a(n-2) +2*(-248*n^2+1666*n-2223)*a(n-3) +(-50*n^2-497*n+3243)*a(n-4) +(-52*n^2+80*n+765)*a(n-5) +3*(22*n-83)*(n-6)*a(n-6)=0. - R. J. Mathar, Jun 24 2020

A027089 a(n) = A027082(n, 2n-2).

Original entry on oeis.org

1, 5, 14, 39, 108, 299, 828, 2299, 6401, 17875, 50062, 140601, 395933, 1117737, 3162812, 8969267, 25487555, 72565339, 206969662, 591304797, 1691991626, 4848703909, 13914119144, 39980978277, 115023510495, 331303274449
Offset: 2

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Cf. A027082.

Formula

Conjecture: D-finite with recurrence -(n+2)*(244*n-1065)*a(n) +3*(n+1)*(422*n -1703)*a(n-1) +2*(-359*n^2 +1211*n -1420)*a(n-2) +2*(-1174*n^2 +6319*n -7410)*a(n-3) +(-760*n^2 +2173*n +1616)*a(n-4) +(-502*n^2 +2245*n -1123)*a(n-5) +6*(23*n-67) *(n-5)*a(n-6)=0. - R. J. Mathar, Jun 24 2020

A027090 a(n) = A027082(n, 2n-3).

Original entry on oeis.org

1, 3, 9, 28, 84, 246, 714, 2059, 5917, 16971, 48633, 139333, 399267, 1144669, 3283839, 9427981, 27090715, 77911897, 224272499, 646157234, 1863317958, 5377939756, 15535195892, 44913790501, 129955421387, 376313609029
Offset: 2

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A027091 a(n) = A027082(n, 2n-4).

Original entry on oeis.org

1, 1, 5, 17, 54, 169, 517, 1559, 4653, 13787, 40638, 119333, 349469, 1021433, 2981330, 8693467, 25333627, 73795263, 214915073, 625855927, 1822630172, 5308552227, 15464475465, 45060652609, 131334677147, 382907083385
Offset: 2

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Crossrefs

Cf. A027082.
Showing 1-10 of 32 results. Next