OFFSET
0,5
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..500
FORMULA
G.f.: exp(Sum_{k>=1} x^k * Sum_{d|k} 1/(d*(1+x)^d)).
MATHEMATICA
m = 40; CoefficientList[Series[Product[1/(1 - x^k/(1 + x)), {k, 1, m}], {x, 0, m}], x] (* Amiram Eldar, May 14 2021 *)
PROG
(PARI) N=66; x='x+O('x^N); Vec(1/prod(k=1, N, 1-x^k/(1+x)))
(PARI) N=66; x='x+O('x^N); Vec(exp(sum(k=1, N, x^k*sumdiv(k, d, 1/(d*(1+x)^d)))))
CROSSREFS
KEYWORD
sign
AUTHOR
Seiichi Manyama, Apr 19 2019
STATUS
approved