a(0)=1, a(n) = a(n-1) + 8*10^(n-1).

Terms

a(0) =1a(1) =9a(2) =89a(3) =889a(4) =8889a(5) =88889a(6) =888889a(7) =8888889a(8) =88888889a(9) =888888889a(10) =8888888889a(11) =88888888889a(12) =888888888889