a(n) = a(n-1) + 9*a(n-2) - 9*a(n-3), where a(0) = 1, a(1) = 5, a(2) = 11.

Terms

a(0) =1a(1) =5a(2) =11a(3) =47a(4) =101a(5) =425a(6) =911a(7) =3827a(8) =8201a(9) =34445a(10) =73811a(11) =310007a(12) =664301a(13) =2790065a(14) =5978711a(15) =25110587a(16) =53808401a(17) =225995285a(18) =484275611a(19) =2033957567a(20) =4358480501a(21) =18305618105a(22) =39226324511a(23) =164750562947a(24) =353036920601