a(n) = 8*10^n - 7.

Terms

a(0) =1a(1) =73a(2) =793a(3) =7993a(4) =79993a(5) =799993a(6) =7999993a(7) =79999993a(8) =799999993a(9) =7999999993a(10) =79999999993a(11) =799999999993