a(n) = 3^n*F(n+2).

Terms

a(0) =1a(1) =6a(2) =27a(3) =135a(4) =648a(5) =3159a(6) =15309a(7) =74358a(8) =360855a(9) =1751787a(10) =8503056a(11) =41275251a(12) =200353257a(13) =972537030a(14) =4720790403a(15) =22915204479a(16) =111232727064a(17) =539935021503