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

Terms

a(0) =1a(1) =2a(2) =-3a(3) =-14a(4) =22a(5) =138a(6) =-213a(7) =-1536a(8) =2474a(9) =18928a(10) =-31451a(11) =-248992a(12) =420804a(13) =3416514a(14) =-5844716a(15) =-48349920a(16) =83503128a(17) =700674606a(18) =-1219159874a(19) =-10345673158a(20) =18109290380a(21) =155082913608a(22) =-272798814028