A022701 Expansion of Product_{m>=1} 1/(1 + m*q^m)^9.

1, -9, 27, -30, 72, -387, 738, -801, 2889, -8119, 13005, -25038, 57735, -122643, 247788, -432786, 862497, -1944657, 3520721, -6191280, 12743919, -24916977, 45349101, -83116206, 156731304, -299550636, 547421607

Offset: 0

Author

N. J. A. Sloane

Keywords

• sign

Links

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

Crossrefs

Column k=9 of A297325.

Programs

Mathematica

With[{nmax = 50}, CoefficientList[Series[Product[(1 + k*q^k)^-9, {k, 1, nmax}], {q, 0, nmax}], q]] (* G. C. Greubel, Jul 19 2018 *)

PARI

m=50; q='q+O('q^m); Vec(prod(n=1,m,(1+n*q^n)^-9)) \\ G. C. Greubel, Jul 19 2018

Formula

G.f.: exp(-9*Sum_{j>=1} Sum_{k>=1} (-1)^(j+1)*k^j*x^(j*k)/j). - Ilya Gutkovskiy, Feb 08 2018