a(n) = 1^n + 3^n + 6^n.

Terms

a(0) =3a(1) =10a(2) =46a(3) =244a(4) =1378a(5) =8020a(6) =47386a(7) =282124a(8) =1686178a(9) =10097380a(10) =60525226a(11) =362974204a(12) =2177313778a(13) =13062288340a(14) =78368947066a(15) =470199333484