G.f. satisfies: A(x) = 1 + x*A(x)^2 + x^2/A(x)^3.

Terms

a(0) =1a(1) =1a(2) =3a(3) =4a(4) =11a(5) =53a(6) =146a(7) =366a(8) =1563a(9) =5837a(10) =16720a(11) =59917a(12) =246090a(13) =828157a(14) =2773984a(15) =11056545a(16) =41539923a(17) =142602611a(18) =536781500a(19) =2103092222a(20) =7632057148a(21) =27948758125a(22) =108960963441a(23) =413531196001