a(n) = Fibonacci(n) - 4.

Terms

a(0) =1a(1) =4a(2) =9a(3) =17a(4) =30a(5) =51a(6) =85a(7) =140a(8) =229a(9) =373a(10) =606a(11) =983a(12) =1593a(13) =2580a(14) =4177a(15) =6761a(16) =10942a(17) =17707a(18) =28653a(19) =46364a(20) =75021a(21) =121389a(22) =196414a(23) =317807a(24) =514225a(25) =832036a(26) =1346265a(27) =2178305a(28) =3524574a(29) =5702883