OFFSET
0,4
FORMULA
a(n) = n! * Sum_{k=0..floor(n/3)} (n+1)^(k-1) * Stirling2(n-2*k,k)/(n-2*k)!.
E.g.f.: (1/x) * Series_Reversion( x*exp(x^2*(1 - exp(x))) ). - Seiichi Manyama, Sep 21 2024
PROG
(PARI) a(n) = n!*sum(k=0, n\3, (n+1)^(k-1)*stirling(n-2*k, k, 2)/(n-2*k)!);
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Mar 13 2024
STATUS
approved