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

Terms

a(0) =1a(1) =1a(2) =1a(3) =3a(4) =8a(5) =20a(6) =55a(7) =159a(8) =464a(9) =1383a(10) =4200a(11) =12910a(12) =40112a(13) =125832a(14) =397888a(15) =1266848a(16) =4058263a(17) =13070453a(18) =42297553a(19) =137467673a(20) =448499679a(21) =1468388784a(22) =4822816903a(23) =15886282268a(24) =52468807845a(25) =173718343364a(26) =576466929104