a(n) = n^3*4^n.

Terms

a(0) =0a(1) =4a(2) =128a(3) =1728a(4) =16384a(5) =128000a(6) =884736a(7) =5619712a(8) =33554432a(9) =191102976a(10) =1048576000a(11) =5582618624a(12) =28991029248a(13) =147438174208a(14) =736586891264