a(n) = 10^n - n.

Terms

a(0) =1a(1) =9a(2) =98a(3) =997a(4) =9996a(5) =99995a(6) =999994a(7) =9999993a(8) =99999992a(9) =999999991a(10) =9999999990a(11) =99999999989a(12) =999999999988