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

Terms

a(0) =2a(1) =1a(2) =2a(3) =1a(4) =4a(5) =7a(6) =10a(7) =15a(8) =26a(9) =43a(10) =68a(11) =109a(12) =178a(13) =289a(14) =466a(15) =753a(16) =1220a(17) =1975a(18) =3194a(19) =5167a(20) =8362a(21) =13531a(22) =21892a(23) =35421a(24) =57314a(25) =92737a(26) =150050a(27) =242785a(28) =392836a(29) =635623