G.f. satisfies A(x) = 1 + x^4*A(x)^3 / (1 - x*A(x)).

Terms

a(0) =1a(1) =0a(2) =0a(3) =0a(4) =1a(5) =1a(6) =1a(7) =1a(8) =4a(9) =8a(10) =13a(11) =19a(12) =38a(13) =79a(14) =153a(15) =273a(16) =509a(17) =999a(18) =1979a(19) =3818a(20) =7331a(21) =14279a(22) =28189a(23) =55599a(24) =109275a(25) =215165a(26) =426093a(27) =846638a(28) =1683215a(29) =3348212