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

Terms

a(0) =1a(1) =1a(2) =5a(3) =30a(4) =220a(5) =1725a(6) =14356a(7) =124020a(8) =1102770a(9) =10023680a(10) =92722620a(11) =870039474a(12) =8261024380a(13) =79225392830a(14) =766302511445