OFFSET
0,5
FORMULA
a(n) = n! * Sum_{k=0..floor(n/3)} (-1)^k * binomial(n/3-1,k)/(n-3*k)!.
a(n) == 1 mod 8.
PROG
(PARI) a(n) = n!*sum(k=0, n\3, (-1)^k*binomial(n/3-1, k)/(n-3*k)!);
CROSSREFS
KEYWORD
sign
AUTHOR
Seiichi Manyama, Jun 09 2024
STATUS
approved