OFFSET
0,3
FORMULA
a(0) = 1; a(n) = Sum_{k=1..n} binomial(n,k) * A000085(k) * a(n-k).
a(n) ~ n! / (2 * sqrt(1 + 2*log(2)) * (sqrt(1 + 2*log(2)) - 1)^(n+1)). - Vaclav Kotesovec, Aug 15 2021
MATHEMATICA
nmax = 20; CoefficientList[Series[1/(2 - Exp[x + x^2/2]), {x, 0, nmax}], x] Range[0, nmax]!
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Aug 09 2021
STATUS
approved