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

Terms

a(0) =1a(1) =1a(2) =2a(3) =5a(4) =12a(5) =29a(6) =70a(7) =169a(8) =408a(9) =985a(10) =2378a(11) =5741a(12) =13860a(13) =33461a(14) =80782a(15) =195025a(16) =470832a(17) =1136689a(18) =2744210a(19) =6625109a(20) =15994428a(21) =38613965a(22) =93222358a(23) =225058681a(24) =543339720a(25) =1311738121a(26) =3166815962a(27) =7645370045a(28) =18457556052a(29) =44560482149