G.f. satisfies A(x) = 1/(1 - x) + x/A(x).

Terms

a(0) =1a(1) =2a(2) =-1a(3) =6a(4) =-17a(5) =71a(6) =-292a(7) =1284a(8) =-5807a(9) =26961a(10) =-127627a(11) =613815a(12) =-2990680a(13) =14730714a(14) =-73229290a(15) =366936232a(16) =-1851352819a(17) =9397497759a(18) =-47957377933a(19) =245903408245