a(n) = 2*a(n - 2) + a(n - 4) with a(0) = a(1) = 2, a(2) = 1, a(3) = 3.

Terms

a(0) =2a(1) =2a(2) =1a(3) =3a(4) =4a(5) =8a(6) =9a(7) =19a(8) =22a(9) =46a(10) =53a(11) =111a(12) =128a(13) =268a(14) =309a(15) =647a(16) =746a(17) =1562a(18) =1801a(19) =3771a(20) =4348a(21) =9104a(22) =10497a(23) =21979a(24) =25342a(25) =53062a(26) =61181a(27) =128103a(28) =147704a(29) =309268