a(n) = 10^n - n^3.

Terms

a(0) =1a(1) =9a(2) =92a(3) =973a(4) =9936a(5) =99875a(6) =999784a(7) =9999657a(8) =99999488a(9) =999999271a(10) =9999999000a(11) =99999998669a(12) =999999998272