A022712 Expansion of Product_{m>=1} (1+m*q^m)^-20.

1, -20, 170, -800, 2415, -6404, 21550, -71080, 178295, -419200, 1203282, -3294360, 7476320, -17381780, 44919500, -107605880, 237628435, -544086720, 1273805460, -2864694880, 6256648862, -13710129840

Offset: 0

Author

N. J. A. Sloane

Keywords

• sign

Links

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

Programs

Mathematica

With[{nmax = 50}, CoefficientList[Series[Product[(1 + k*q^k)^-20, {k, 1, nmax}], {q, 0, nmax}], q]] (* G. C. Greubel, Jul 20 2018 *)

PARI

m=50; q='q+O('q^m); Vec(prod(n=1,m,(1+n*q^n)^-20)) \\ G. C. Greubel, Jul 20 2018