OFFSET
0,12
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..1000
FORMULA
G.f.: exp(Sum_{k>=1} x^k * Sum_{d|k} (-1)^(d+1)*(1 - x)^d/d). - Ilya Gutkovskiy, Apr 16 2019
MATHEMATICA
With[{nn=70}, CoefficientList[Series[Product[1+x^k (1-x), {k, nn}], {x, 0, nn}], x]] (* Harvey P. Dale, Aug 03 2020 *)
PROG
(PARI) N=66; x='x+O('x^N); Vec(prod(k=1, N, 1+x^k*(1-x)))
CROSSREFS
KEYWORD
sign
AUTHOR
Seiichi Manyama, Apr 16 2019
STATUS
approved