OFFSET
0,3
FORMULA
E.g.f.: d/dx log(Product_{k>=1} (1 + x^k)). - Ilya Gutkovskiy, Oct 15 2017
a(n) = n! * A000593(n+1). - Seiichi Manyama, Nov 08 2020.
E.g.f.: d/dx ( Sum_{k>=1} x^k / (k * (1 - x^(2*k))) ). - Seiichi Manyama, Sep 18 2021
MATHEMATICA
Rest[CoefficientList[Series[Log[QPochhammer[-1, x]/2], {x, 0, 20}], x] * Range[0, 20]!] (* Vaclav Kotesovec, Oct 15 2017 *)
PROG
(Sage)
A265024 = lambda n: factorial(n)*sum((-1)^(d+1)*(n+1)/d for d in divisors(n+1))
[A265024(n) for n in (0..21)]
(PARI) a(n) = n!*sumdiv(n+1, d, (-1)^(d+1)*(n+1)/d); \\ Michel Marcus, Jan 26 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
Peter Luschny, Jan 26 2016
STATUS
approved