OFFSET
1,2
LINKS
Vaclav Kotesovec, Table of n, a(n) for n = 1..200
FORMULA
exp(Sum_{n>=1} a(n) * x^n / n) = g.f. of A000670.
a(n) ~ n * n! / (2 * (log(2))^(n+1)). - Vaclav Kotesovec, Jan 28 2020
MATHEMATICA
nmax = 20; CoefficientList[Series[Log[Sum[k! x^k/Product[1 - j x, {j, 1, k}], {k, 0, nmax}]], {x, 0, nmax}], x] Range[0, nmax] // Rest
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Jan 14 2020
STATUS
approved