a(n) = 8^n + n^8.

Terms

a(0) =1a(1) =9a(2) =320a(3) =7073a(4) =69632a(5) =423393a(6) =1941760a(7) =7861953a(8) =33554432a(9) =177264449a(10) =1173741824a(11) =8804293473a(12) =69149458432a(13) =550571544609