G.f. satisfies A(x) = exp( 2 * Sum_{k>=1} A(-x^k) * x^k/k ).

Terms

a(0) =1a(1) =2a(2) =-1a(3) =-6a(4) =7a(5) =42a(6) =-58a(7) =-366a(8) =513a(9) =3406a(10) =-4846a(11) =-33310a(12) =48304a(13) =339446a(14) =-499133a(15) =-3565468a(16) =5294439a(17) =38312242a(18) =-57332347a(19) =-419177900a(20) =631252549a(21) =4654229300a(22) =-7045498256a(23) =-52310262192a(24) =79531957334a(25) =593986308994a(26) =-906439292326