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

Terms

a(0) =1a(1) =0a(2) =3a(3) =2a(4) =25a(5) =94a(6) =721a(7) =3674a(8) =42561a(9) =291248a(10) =3628801a(11) =34254604a(12) =479001601a(13) =5337581534a(14) =88966701825