a(n) = n*(n-1)^(n-1).

Terms

a(0) =1a(1) =2a(2) =12a(3) =108a(4) =1280a(5) =18750a(6) =326592a(7) =6588344a(8) =150994944a(9) =3874204890a(10) =110000000000