a(n) = (-1)^(p-1)*(p-1)! + 1 where p = prime(n).

A062411

a(n) = (-1)^(p-1)*(p-1)! + 1 where p = prime(n).

Terms

    a(0) =0a(1) =3a(2) =25a(3) =721a(4) =3628801a(5) =479001601

External references