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

Terms

a(0) =1a(1) =2a(2) =1a(3) =3a(4) =6a(5) =9a(6) =13a(7) =22a(8) =37a(9) =59a(10) =94a(11) =153a(12) =249a(13) =402a(14) =649a(15) =1051a(16) =1702a(17) =2753a(18) =4453a(19) =7206a(20) =11661a(21) =18867a(22) =30526a(23) =49393a(24) =79921a(25) =129314a(26) =209233a(27) =338547a(28) =547782a(29) =886329