G.f. satisfies A(x) = 1 + x*A(x)^4 / (1 + x*A(x)^5).

Terms

a(0) =1a(1) =1a(2) =3a(3) =10a(4) =30a(5) =56a(6) =-167a(7) =-2813a(8) =-21515a(9) =-126135a(10) =-601812a(11) =-2179039a(12) =-3455504a(13) =32238155a(14) =430944400a(15) =3334419890a(16) =20083350422a(17) =97094186751a(18) =338485665435a(19) =274332822425