OFFSET
0,3
LINKS
Robert Israel, Table of n, a(n) for n = 0..2000
FORMULA
G.f.: exp(Sum_{k>=1} (-1)^(k+1)*x^k/(k*(1 + x^k)^2)). - Ilya Gutkovskiy, Jun 20 2018
MAPLE
N:= 100: # to get a(0)..a(N)
P:= mul((1+x^(2*k-1))^(2*k-1)/(1+x^(2*k))^(2*k), k=1..N/2):
S:= series(P, x, N+1):
seq(coeff(S, x, j), j=0..N); # Robert Israel, Apr 16 2017
MATHEMATICA
nmax = 60; CoefficientList[Series[Product[(1 + x^(2*k-1))^(2*k-1)/(1 + x^(2*k))^(2*k), {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Apr 15 2017 *)
CROSSREFS
KEYWORD
sign
AUTHOR
Seiichi Manyama, Apr 15 2017
STATUS
approved