a(n) = Sum_{m=0..n} m*n^(m-1).

Terms

a(0) =0a(1) =1a(2) =5a(3) =34a(4) =313a(5) =3711a(6) =54121a(7) =937924a(8) =18831569a(9) =429794605a(10) =10987654321a(11) =310989720966