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

Terms

a(0) =1a(1) =0a(2) =0a(3) =1a(4) =3a(5) =6a(6) =13a(7) =33a(8) =84a(9) =208a(10) =522a(11) =1341a(12) =3476a(13) =9042a(14) =23673a(15) =62426a(16) =165504a(17) =440664a(18) =1178168a(19) =3162357a(20) =8517681a(21) =23013294a(22) =62356329a(23) =169408107a(24) =461366499a(25) =1259311824a(26) =3444497550a(27) =9439766700a(28) =25916832981a(29) =71274793968