a(n) = 5^n * n*(n + 1).

Terms

a(0) =0a(1) =10a(2) =150a(3) =1500a(4) =12500a(5) =93750a(6) =656250a(7) =4375000a(8) =28125000a(9) =175781250a(10) =1074218750a(11) =6445312500a(12) =38085937500a(13) =222167968750