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.

A273226 G.f. is the cube of the g.f. of A006950.

Original entry on oeis.org

1, 3, 6, 13, 27, 51, 91, 159, 273, 455, 738, 1179, 1860, 2886, 4410, 6667, 9981, 14781, 21671, 31512, 45474, 65113, 92547, 130689, 183439, 255930, 355017, 489895, 672672, 919152, 1250107, 1692846, 2282895, 3066180, 4102224, 5468160, 7263217, 9614436, 12684633, 16682276
Offset: 0

Views

Author

M.S. Mahadeva Naika, May 18 2016

Keywords

Crossrefs

Cf. A006950.

Programs

  • Maple
    N:= 50:
    G:= mul((1+x^k)^3,k=1..N)/mul((1-x^(4*k))^3,k=1..N/4):
    S:= series(G,x,N+1):
    seq(coeff(S,x,j),j=0..N); # Robert Israel, Jan 21 2019
  • Mathematica
    s = QPochhammer[-1, x]^3/(8*QPochhammer[x^4, x^4]^3) + O[x]^40; CoefficientList[s, x] (* Jean-François Alcover, May 20 2016 *)

Formula

G.f.: Product_{k>=1} (1 + x^k)^3 / (1 - x^(4*k))^3, corrected by Vaclav Kotesovec, Mar 25 2017.
a(n) ~ 3*exp(sqrt(3*n/2)*Pi) / (16*n^(3/2)). - Vaclav Kotesovec, Mar 25 2017

Extensions

Edited by N. J. A. Sloane, May 26 2016