a(n) = 2^n + 6^n + 8^n.

Terms

a(0) =3a(1) =16a(2) =104a(3) =736a(4) =5408a(5) =40576a(6) =308864a(7) =2377216a(8) =18457088a(9) =144295936a(10) =1134209024a(11) =8952733696a(12) =70896263168a(13) =562816516096