a(n) = 2^n + 3^n + 6^n.

Terms

a(0) =3a(1) =11a(2) =49a(3) =251a(4) =1393a(5) =8051a(6) =47449a(7) =282251a(8) =1686433a(9) =10097891a(10) =60526249a(11) =362976251a(12) =2177317873a(13) =13062296531a(14) =78368963449a(15) =470199366251