a(n) = 10^n - n^8.

Terms

a(0) =1a(1) =9a(2) =-156a(3) =-5561a(4) =-55536a(5) =-290625a(6) =-679616a(7) =4235199a(8) =83222784a(9) =956953279a(10) =9900000000a(11) =99785641119a(12) =999570018304