G.f. A(x) satisfies A(3*x^2) = 2*x^2 + A(x)^2 - 2*A(x)^3.

Terms

a(0) =1a(1) =1a(2) =7a(3) =17a(4) =147a(5) =445a(6) =2199a(7) =9993a(8) =61837a(9) =281417a(10) =1515387a(11) =7844861a(12) =42920817a(13) =232527741a(14) =1297380639a(15) =7159441425a(16) =40375866078a(17) =226515725383