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

Terms

a(0) =1a(1) =1a(2) =5a(3) =13a(4) =41a(5) =121a(6) =365a(7) =1093a(8) =3281a(9) =9841a(10) =29525a(11) =88573a(12) =265721a(13) =797161a(14) =2391485a(15) =7174453a(16) =21523361a(17) =64570081a(18) =193710245a(19) =581130733a(20) =1743392201a(21) =5230176601a(22) =15690529805a(23) =47071589413a(24) =141214768241a(25) =423644304721