a(n) = 10^n - n^5.

Terms

a(0) =1a(1) =9a(2) =68a(3) =757a(4) =8976a(5) =96875a(6) =992224a(7) =9983193a(8) =99967232a(9) =999940951a(10) =9999900000a(11) =99999838949a(12) =999999751168