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

Terms

a(0) =2a(1) =14a(2) =100a(3) =728a(4) =5392a(5) =40544a(6) =308800a(7) =2377088a(8) =18456832a(9) =144295424a(10) =1134208000a(11) =8952731648a(12) =70896259072a(13) =562816507904