G.f. A(x) satisfies: A(x) = Sum_{n>=0} x^n/(1 - x^2*A(x)^n).

Terms

a(0) =1a(1) =1a(2) =2a(3) =2a(4) =4a(5) =7a(6) =16a(7) =38a(8) =97a(9) =257a(10) =704a(11) =1985a(12) =5742a(13) =17013a(14) =51532a(15) =159356a(16) =502470a(17) =1613880a(18) =5275917a(19) =17543426a(20) =59307258a(21) =203759160a(22) =711246902a(23) =2521876015a(24) =9081377033a(25) =33207738613a(26) =123289411854a(27) =464675856111