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

Terms

a(0) =2a(1) =2a(2) =2a(3) =1a(4) =5a(5) =9a(6) =12a(7) =18a(8) =32a(9) =53a(10) =83a(11) =133a(12) =218a(13) =354a(14) =570a(15) =921a(16) =1493a(17) =2417a(18) =3908a(19) =6322a(20) =10232a(21) =16557a(22) =26787a(23) =43341a(24) =70130a(25) =113474a(26) =183602a(27) =297073a(28) =480677a(29) =777753