A022621 Expansion of Product_{m>=1} (1+q^m)^(-26).

1, -26, 325, -2626, 15626, -74256, 298831, -1063426, 3447132, -10372882, 29340142, -78744042, 202029633, -498419898, 1187802148, -2744629914, 6168519890, -13520237380, 28964225680, -60763817556, 125042511217, -252773944748, 502601225828, -984061449124, 1899179853506

Offset: 0

Author

N. J. A. Sloane

Keywords

• sign

Links

• G. C. Greubel, Table of n, a(n) for n = 0..1000

Programs

Mathematica

nmax = 50; CoefficientList[Series[Product[1/(1 + x^k)^26, {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Aug 27 2015 *)

Formula

a(n) ~ (-1)^n * 13^(1/4) * exp(Pi*sqrt(13*n/3)) / (2^(3/2) * 3^(1/4) * n^(3/4)). - Vaclav Kotesovec, Aug 27 2015