a(n) = a(n-2) + a(n-3) + a(n-4), with initial values a(0) = 0, a(1) = 2, a(2) = 3, a(3) = 6.

Terms

a(0) =0a(1) =2a(2) =3a(3) =6a(4) =5a(5) =11a(6) =14a(7) =22a(8) =30a(9) =47a(10) =66a(11) =99a(12) =143a(13) =212a(14) =308a(15) =454a(16) =663a(17) =974a(18) =1425a(19) =2091a(20) =3062a(21) =4490a(22) =6578a(23) =9643a(24) =14130a(25) =20711a(26) =30351a(27) =44484a(28) =65192a(29) =95546