a(n) = 3*Fibonacci(n) + (-1)^n.

Terms

a(0) =1a(1) =2a(2) =4a(3) =5a(4) =10a(5) =14a(6) =25a(7) =38a(8) =64a(9) =101a(10) =166a(11) =266a(12) =433a(13) =698a(14) =1132a(15) =1829a(16) =2962a(17) =4790a(18) =7753a(19) =12542a(20) =20296a(21) =32837a(22) =53134a(23) =85970a(24) =139105a(25) =225074a(26) =364180a(27) =589253a(28) =953434a(29) =1542686