OFFSET
0,2
FORMULA
a(n) = n! * Sum_{k=0..n} (n+k+1)^(k-1) * binomial(2*n,n-k)/k!.
PROG
(PARI) a(n) = n!*sum(k=0, n, (n+k+1)^(k-1)*binomial(2*n, n-k)/k!);
CROSSREFS
KEYWORD
nonn,new
AUTHOR
Seiichi Manyama, Jan 30 2025
STATUS
approved