OFFSET
0,3
FORMULA
a(n) = (1/(4*n+1)!) * Sum_{k=0..n} (4*n+k)! * Stirling2(n,k).
PROG
(PARI) a(n) = sum(k=0, n, (4*n+k)!*stirling(n, k, 2))/(4*n+1)!;
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Oct 28 2024
STATUS
approved