a(n) = 8*6^n+1.

Terms

a(0) =9a(1) =49a(2) =289a(3) =1729a(4) =10369a(5) =62209a(6) =373249a(7) =2239489a(8) =13436929a(9) =80621569a(10) =483729409a(11) =2902376449a(12) =17414258689a(13) =104485552129a(14) =626913312769