G.f. satisfies: A(x) = 1 + x*A(x+x^2)^2.

Terms

a(0) =1a(1) =1a(2) =2a(3) =7a(4) =28a(5) =133a(6) =700a(7) =4039a(8) =25160a(9) =167637a(10) =1186482a(11) =8872752a(12) =69810994a(13) =575912978a(14) =4967058182a(15) =44675926159a(16) =418157494016