a(n) = (n-1)! * Sum_{d|n} d^(n/d) / (d-1)!.

Terms

a(0) =1a(1) =3a(2) =5a(3) =34a(4) =29a(5) =1626a(6) =727a(7) =99128a(8) =584649a(9) =12353050a(10) =3628811a(11) =4648976652a(12) =479001613a(13) =803709466574