a(n) = (3*n + 2)^8.

Terms

a(0) =256a(1) =390625a(2) =16777216a(3) =214358881a(4) =1475789056a(5) =6975757441a(6) =25600000000a(7) =78310985281a(8) =208827064576a(9) =500246412961