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

Terms

a(0) =0a(1) =2a(2) =21a(3) =228a(4) =2930a(5) =44790a(6) =800667a(7) =16434824a(8) =381367044a(9) =9876543210a(10) =282458553905