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

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =6a(5) =22a(6) =95a(7) =463a(8) =2483a(9) =14426a(10) =89799a(11) =594038a(12) =4150514a(13) =30482791a(14) =234428282a(15) =1881944298a(16) =15729230166a(17) =136566166388