E.g.f. satisfies A(x) = exp(x*A(x^4/4!)).

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =6a(6) =31a(7) =106a(8) =281a(9) =946a(10) =7561a(11) =54286a(12) =281161a(13) =1207636a(14) =7997991a(15) =81996916a(16) =701522641a(17) =4580581916a(18) =29742355441a(19) =306369616636