OFFSET
0,3
FORMULA
a(n) = Sum_{k=0..n} (3*n+2*k)!/(3*n+k+1)! * Stirling2(n,k).
PROG
(PARI) a(n) = sum(k=0, n, (3*n+2*k)!/(3*n+k+1)!*stirling(n, k, 2));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Oct 25 2024
STATUS
approved