OFFSET
0,3
FORMULA
a(0) = 1; a(n) = Sum_{k=1..n} binomial(n-1,k-1) * A000085(k) * a(n-k).
MATHEMATICA
nmax = 22; CoefficientList[Series[Exp[Exp[x + x^2/2] - 1], {x, 0, nmax}], x] Range[0, nmax]!
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Aug 09 2021
STATUS
approved