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

Terms

a(0) =1a(1) =8a(2) =-431a(3) =-18954a(4) =-255583a(5) =-1894076a(6) =-9546255a(7) =-35570638a(8) =-91171007a(9) =0a(10) =2486784401a(11) =29023111918a(12) =277269756129