a(n) = a(n-1) + 5*a(n-2) for n >= 2, a(0)=1, a(1)=2.

Terms

a(0) =1a(1) =2a(2) =7a(3) =17a(4) =52a(5) =137a(6) =397a(7) =1082a(8) =3067a(9) =8477a(10) =23812a(11) =66197a(12) =185257a(13) =516242a(14) =1442527a(15) =4023737a(16) =11236372a(17) =31355057a(18) =87536917a(19) =244312202a(20) =681996787a(21) =1903557797a(22) =5313541732a(23) =14831330717a(24) =41399039377a(25) =115555692962a(26) =322550889847a(27) =900329354657