a(n) = Sum_{i=2..n-1} i*n^(i-2).

Terms

a(0) =0a(1) =0a(2) =0a(3) =2a(4) =14a(5) =117a(6) =1244a(7) =16340a(8) =256794a(9) =4708235a(10) =98765432a(11) =2334368214a(12) =61405650470