a(n) = 9^n - n^6.

Terms

a(0) =1a(1) =8a(2) =17a(3) =0a(4) =2465a(5) =43424a(6) =484785a(7) =4665320a(8) =42784577a(9) =386889048a(10) =3485784401a(11) =31379288048a(12) =282426550497