OFFSET
0,4
FORMULA
a(n) = n! * Sum_{k=0..floor(n/2)} Stirling2(k,n-2*k)/(2^k*k!).
PROG
(PARI) my(N=30, x='x+O('x^N)); Vec(serlaplace(exp(x*(exp(x^2/2)-1))))
(PARI) a(n) = n!*sum(k=0, n\2, stirling(k, n-2*k, 2)/(2^k*k!));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Aug 19 2024
STATUS
approved