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

Terms

a(0) =2a(1) =1a(2) =0a(3) =1a(4) =4a(5) =5a(6) =6a(7) =11a(8) =20a(9) =31a(10) =48a(11) =79a(12) =130a(13) =209a(14) =336a(15) =545a(16) =884a(17) =1429a(18) =2310a(19) =3739a(20) =6052a(21) =9791a(22) =15840a(23) =25631a(24) =41474a(25) =67105a(26) =108576a(27) =175681a(28) =284260a(29) =459941