207217domain: NAppears in sequencesG.f.: A(x) = (A_1)^2 where A_1 = 1/[1 - x*(A_2)^2], A_2 = 1/[1 - x^2*(A_3)^2], A_3 = 1/[1 - x^3*(A_4)^2], ... A_n = 1/[1 - x^n*(A_{n+1})^2] for n>=1.at n=16A132333Coefficients of g.f. for the class of C-trees.at n=8A280767