E.g.f.: exp(1/((1+x)*(1+x^2)) - 1).

Terms

a(0) =1a(1) =-1a(2) =1a(3) =-1a(4) =25a(5) =-241a(6) =1081a(7) =-3361a(8) =68881a(9) =-1288225a(10) =11828881a(11) =-69917761a(12) =1347298921a(13) =-36402297361a(14) =533785676425