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

Terms

a(0) =1a(1) =2a(2) =2a(3) =1a(4) =4a(5) =8a(6) =11a(7) =16a(8) =28a(9) =47a(10) =74a(11) =118a(12) =193a(13) =314a(14) =506a(15) =817a(16) =1324a(17) =2144a(18) =3467a(19) =5608a(20) =9076a(21) =14687a(22) =23762a(23) =38446a(24) =62209a(25) =100658a(26) =162866a(27) =263521a(28) =426388a(29) =689912