OFFSET
0,7
FORMULA
a(n) = n! * Sum_{k=0..n} 2^k * k^(n-k) * binomial(1/2,k)/(n-k)!.
PROG
(PARI) a(n) = n!*sum(k=0, n, 2^k*k^(n-k)*binomial(1/2, k)/(n-k)!);
CROSSREFS
KEYWORD
sign
AUTHOR
Seiichi Manyama, Jan 12 2025
STATUS
approved