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

Terms

a(0) =1a(1) =1a(2) =2a(3) =-2a(4) =0a(5) =3a(6) =3a(7) =1a(8) =4a(9) =10a(10) =14a(11) =19a(12) =33a(13) =57a(14) =90a(15) =142a(16) =232a(17) =379a(18) =611a(19) =985a(20) =1596a(21) =2586a(22) =4182a(23) =6763a(24) =10945a(25) =17713a(26) =28658a(27) =46366a(28) =75024a(29) =121395