a(n) = Fibonacci(n+3) - 2.

Terms

a(0) =0a(1) =1a(2) =3a(3) =6a(4) =11a(5) =19a(6) =32a(7) =53a(8) =87a(9) =142a(10) =231a(11) =375a(12) =608a(13) =985a(14) =1595a(15) =2582a(16) =4179a(17) =6763a(18) =10944a(19) =17709a(20) =28655a(21) =46366a(22) =75023a(23) =121391a(24) =196416a(25) =317809a(26) =514227a(27) =832038a(28) =1346267a(29) =2178307