G.f. satisfies: A(x) = x + A( x*A(x)/(1 - x*A(x)) ).

Terms

a(0) =1a(1) =1a(2) =1a(3) =3a(4) =7a(5) =17a(6) =45a(7) =121a(8) =333a(9) =937a(10) =2675a(11) =7735a(12) =22613a(13) =66711a(14) =198361a(15) =593873a(16) =1788697a(17) =5416097a(18) =16477471a(19) =50342595a(20) =154397465a(21) =475169249a(22) =1466983101a(23) =4542061223a(24) =14100318843a(25) =43879550851a(26) =136858661589a(27) =427747723605