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

Terms

a(0) =1a(1) =3a(2) =11a(3) =37a(4) =129a(5) =443a(6) =1531a(7) =5277a(8) =18209a(9) =62803a(10) =216651a(11) =747317a(12) =2577889a(13) =8892363a(14) =30674171a(15) =105810157a(16) =364991169a(17) =1259033123a(18) =4343022091a(19) =14981209797a(20) =51677530049a(21) =178261109083a(22) =614909868411