a(n) = 8^n - 7^n + 1.

Terms

a(0) =1a(1) =2a(2) =16a(3) =170a(4) =1696a(5) =15962a(6) =144496a(7) =1273610a(8) =11012416a(9) =93864122a(10) =791266576a(11) =6612607850a(12) =54878189536a(13) =452866803482