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

Terms

a(0) =1a(1) =1a(2) =0a(3) =0a(4) =1a(5) =3a(6) =3a(7) =1a(8) =3a(9) =15a(10) =30a(11) =30a(12) =27a(13) =87a(14) =252a(15) =420a(16) =475a(17) =747a(18) =2064a(19) =4632a(20) =7203a(21) =9933a(22) =19635a(23) =47025a(24) =92013a(25) =144745a(26) =237510a(27) =498498a(28) =1073817a(29) =1969131