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

Terms

a(0) =1a(1) =7a(2) =-192a(3) =-6049a(4) =-61440a(5) =-357857a(6) =-1417472a(7) =-3667649a(8) =0a(9) =91171007a(10) =973741824a(11) =8375575711a(12) =68289495040a(13) =548940083167