OFFSET
0,2
FORMULA
a(n) = (n!/(n+1)) * Sum_{k=0..n} 2^(n-k) * (2*n-k+1)^k * binomial(n+1,n-k)/k!.
PROG
(PARI) a(n) = n!*sum(k=0, n, 2^(n-k)*(2*n-k+1)^k*binomial(n+1, n-k)/k!)/(n+1);
CROSSREFS
KEYWORD
nonn,new
AUTHOR
Seiichi Manyama, Dec 30 2024
STATUS
approved