G.f. A(x) satisfies A(x) = ( 1 + 9*x*(1 + x)*A(x) )^(1/3).

Terms

a(0) =1a(1) =3a(2) =3a(3) =-9a(4) =0a(5) =81a(6) =-171a(7) =-621a(8) =3672a(9) =324a(10) =-54918a(11) =125145a(12) =563922a(13) =-3381345a(14) =-1013553a(15) =59036607a(16) =-128956455a(17) =-693917604a(18) =3979050642a(19) =2186515944a(20) =-76048363647a(21) =153593093106a(22) =978492895848