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

Terms

a(0) =1a(1) =0a(2) =1a(3) =1a(4) =6a(5) =12a(6) =54a(7) =147a(8) =593a(9) =1886a(10) =7292a(11) =25204a(12) =96153a(13) =348304a(14) =1327716a(15) =4946471a(16) =18936366a(17) =71827598a(18) =276612103a(19) =1062220253a(20) =4115807184a(21) =15947902376a(22) =62148513732a(23) =242485933208a(24) =949828266722