OFFSET
0,3
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) * (k/d + x)^d / d).
MATHEMATICA
m = 39; CoefficientList[Series[Product[1 + x^k*(k + x), {k, 1, m}], {x, 0, m}], x] (* Amiram Eldar, May 01 2021 *)
PROG
(PARI) N=66; x='x+O('x^N); Vec(prod(k=1, N, 1+x^k*(k+x)))
(PARI) N=66; x='x+O('x^N); Vec(exp(sum(k=1, N, x^k*sumdiv(k, d, (-1)^(d+1)*(k/d+x)^d/d))))
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Aug 09 2020
STATUS
approved