a(n+2) = 5*a(n+1) - 3*a(n).

Terms

a(0) =1a(1) =4a(2) =17a(3) =73a(4) =314a(5) =1351a(6) =5813a(7) =25012a(8) =107621a(9) =463069a(10) =1992482a(11) =8573203a(12) =36888569a(13) =158723236a(14) =682950473a(15) =2938582657a(16) =12644061866a(17) =54404561359a(18) =234090621197