G.f. S(x) satisfies: C(C(x)) + S(S(x)) = x where S(C(x)) = 2*x*C(x).

Terms

a(0) =0a(1) =2a(2) =0a(3) =0a(4) =8a(5) =0a(6) =0a(7) =256a(8) =0a(9) =0a(10) =13312a(11) =0a(12) =0a(13) =868352a(14) =0a(15) =0a(16) =65436672a(17) =0a(18) =0a(19) =5467537408a(20) =0a(21) =0a(22) =494982725632a(23) =0a(24) =0a(26) =0a(27) =0a(29) =0a(30) =0a(32) =0