G.f. A(x) satisfies: A(A(x)) - A(A(x))^2 = x + x^2.

Terms

a(0) =1a(1) =1a(2) =1a(3) =3a(4) =7a(5) =21a(6) =61a(7) =187a(8) =583a(9) =1837a(10) =5885a(11) =19027a(12) =62167a(13) =204917a(14) =680621a(15) =2275211a(16) =7648519a(17) =25852573a(18) =87812093a(19) =299349795a(20) =1023570647a(21) =3515918501a(22) =12140103149a(23) =41894710427a(24) =143835281351a(25) =501071173901