G.f. satisfies: A(x) = 1 + 2*x*A(x) + 5*x^2*A(x)^2.

Terms

a(0) =1a(1) =2a(2) =9a(3) =38a(4) =186a(5) =932a(6) =4889a(7) =26238a(8) =143966a(9) =802652a(10) =4536874a(11) =25932348a(12) =149650516a(13) =870675912a(14) =5101656889a(15) =30078478318a(16) =178309845686