a(n) = (n^3 - n^2)*5^n.

Terms

a(0) =0a(1) =100a(2) =2250a(3) =30000a(4) =312500a(5) =2812500a(6) =22968750a(7) =175000000a(8) =1265625000a(9) =8789062500a(10) =59082031250a(11) =386718750000