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

Terms

a(0) =1a(1) =1a(2) =-3a(3) =3a(4) =11a(5) =-54a(6) =66a(7) =297a(8) =-1575a(9) =1980a(10) =10300a(11) =-55392a(12) =68352a(13) =403583a(14) =-2153685a(15) =2551845a(16) =16999045a(17) =-89142087a(18) =99986901a(19) =750955382a(20) =-3850437018a(21) =4041467331a(22) =34310059311a(23) =-171533033904a(24) =166630375248