OFFSET
0,2
LINKS
Robert Israel, Table of n, a(n) for n = 0..3000
FORMULA
G.f.: exp(-4*Sum_{j>=1} Sum_{k>=1} (-1)^(j+1)*k^j*x^(j*k)/j). - Ilya Gutkovskiy, Feb 08 2018
MAPLE
N:= 100: # to get a(0)..a(N)
P:= mul((1+m*q^m)^(-4), m=1..N):
S:=series(P, q, N+1):
[seq(coeff(S, q, j), j=0..N)]; # Robert Israel, Jan 23 2018
MATHEMATICA
With[{nmax = 50}, CoefficientList[Series[Product[(1 + k*q^k)^-4, {k, 1, nmax}], {q, 0, nmax}], q]] (* G. C. Greubel, Jul 19 2018 *)
PROG
(PARI) m=50; q='q+O('q^m); Vec(prod(n=1, m, (1+n*q^n)^-4)) \\ G. C. Greubel, Jul 19 2018
CROSSREFS
KEYWORD
sign
AUTHOR
STATUS
approved