First differences of 10^n (A011557).

Terms

a(0) =9a(1) =90a(2) =900a(3) =9000a(4) =90000a(5) =900000a(6) =9000000a(7) =90000000a(8) =900000000a(9) =9000000000a(10) =90000000000a(11) =900000000000