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

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =3a(5) =5a(6) =7a(7) =11a(8) =19a(9) =31a(10) =49a(11) =79a(12) =129a(13) =209a(14) =337a(15) =545a(16) =883a(17) =1429a(18) =2311a(19) =3739a(20) =6051a(21) =9791a(22) =15841a(23) =25631a(24) =41473a(25) =67105a(26) =108577a(27) =175681a(28) =284259a(29) =459941