OFFSET
0,3
FORMULA
G.f.: exp(-Sum_{k>=1} sigma(k)*(x*(1+x))^k/k).
MATHEMATICA
nmax = 40; CoefficientList[Series[Product[(1 - (x*(1+x))^k), {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Sep 22 2019 *)
PROG
(PARI) N=66; x='x+O('x^N); Vec(prod(k=1, N, 1-(x*(1+x))^k))
(PARI) N=66; x='x+O('x^N); Vec(exp(-sum(k=1, N, sigma(k)*(x*(1+x))^k/k)))
CROSSREFS
KEYWORD
sign
AUTHOR
Seiichi Manyama, Sep 21 2019
STATUS
approved