a(n) = 9^n + 8.

Terms

a(0) =9a(1) =17a(2) =89a(3) =737a(4) =6569a(5) =59057a(6) =531449a(7) =4782977a(8) =43046729a(9) =387420497a(10) =3486784409a(11) =31381059617a(12) =282429536489