a(n) = 5^n + 6^n + 8^n.

Terms

a(0) =3a(1) =19a(2) =125a(3) =853a(4) =6017a(5) =43669a(6) =324425a(7) =2455213a(8) =18847457a(9) =146248549a(10) =1143973625a(11) =9001559773a(12) =71140399697a(13) =564037211029