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

Terms

a(0) =2a(1) =3a(2) =7a(3) =13a(4) =27a(5) =53a(6) =107a(7) =213a(8) =427a(9) =853a(10) =1707a(11) =3413a(12) =6827a(13) =13653a(14) =27307a(15) =54613a(16) =109227a(17) =218453a(18) =436907a(19) =873813a(20) =1747627a(21) =3495253a(22) =6990507a(23) =13981013a(24) =27962027a(25) =55924053a(26) =111848107a(27) =223696213a(28) =447392427a(29) =894784853