a(n) = (9*n + 5)^6.

Terms

a(0) =15625a(1) =7529536a(2) =148035889a(3) =1073741824a(4) =4750104241a(5) =15625000000a(6) =42180533641a(7) =98867482624a(8) =208422380089a(9) =404567235136a(10) =735091890625