a(n) = 9 + 4 * 10^n.

Terms

a(0) =49a(1) =409a(2) =4009a(3) =40009a(4) =400009a(5) =4000009a(6) =40000009a(7) =400000009a(8) =4000000009a(9) =40000000009a(10) =400000000009