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

Terms

a(0) =2a(1) =0a(2) =1a(3) =1a(4) =3a(5) =4a(6) =6a(7) =10a(8) =17a(9) =27a(10) =43a(11) =70a(12) =114a(13) =184a(14) =297a(15) =481a(16) =779a(17) =1260a(18) =2038a(19) =3298a(20) =5337a(21) =8635a(22) =13971a(23) =22606a(24) =36578a(25) =59184a(26) =95761a(27) =154945a(28) =250707a(29) =405652