a(n) = 8^n + 9^n.

Terms

a(0) =2a(1) =17a(2) =145a(3) =1241a(4) =10657a(5) =91817a(6) =793585a(7) =6880121a(8) =59823937a(9) =521638217a(10) =4560526225a(11) =39970994201a(12) =351149013217