a(n) = 9^n - n^8.

Terms

a(0) =1a(1) =8a(2) =-175a(3) =-5832a(4) =-58975a(5) =-331576a(6) =-1148175a(7) =-981832a(8) =26269505a(9) =344373768a(10) =3386784401a(11) =31166700728a(12) =281999554785