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

Terms

a(0) =1a(1) =1a(2) =3a(3) =14a(4) =78a(5) =475a(6) =3057a(7) =20446a(8) =140702a(9) =989789a(10) =7085635a(11) =51451482a(12) =378049810a(13) =2805616460a(14) =20999408480a(15) =158337719608