OFFSET
0,3
FORMULA
a(n) = n! * Sum_{k=0..n} 3^k * k^(n-k) * binomial(k/3+1/3,k)/( (k+1)*(n-k)! ).
PROG
(PARI) a(n) = n!*sum(k=0, n, 3^k*k^(n-k)*binomial(k/3+1/3, k)/((k+1)*(n-k)!));
CROSSREFS
KEYWORD
sign,new
AUTHOR
Seiichi Manyama, Jan 11 2025
STATUS
approved