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

Terms

a(0) =0a(1) =1a(2) =1a(3) =0a(4) =2a(5) =2a(6) =3a(7) =4a(8) =7a(9) =9a(10) =14a(11) =20a(12) =30a(13) =43a(14) =64a(15) =93a(16) =137a(17) =200a(18) =294a(19) =430a(20) =631a(21) =924a(22) =1355a(23) =1985a(24) =2910a(25) =4264a(26) =6250a(27) =9159a(28) =13424a(29) =19673