G.f. A(x) satisfies A(x) = 1 + x*abs( 1/A(x) )^3.

Terms

a(0) =1a(1) =1a(2) =3a(3) =9a(4) =25a(5) =60a(6) =111a(7) =356a(8) =717a(9) =1728a(10) =3532a(11) =7923a(12) =13947a(13) =43956a(14) =135762a(15) =455844a(16) =1502005a(17) =4377084a(18) =9696816a(19) =33777040a(20) =76261380a(21) =211981800a(22) =491690441a(23) =1156806114a(24) =2388107247a(25) =7425085120a(26) =22208783472a(27) =72885740508a(28) =243066599038a(29) =726160343256