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

Terms

a(0) =1a(1) =1a(2) =-1a(3) =-5a(4) =25a(5) =41a(6) =-1049a(7) =2899a(8) =54545a(9) =-610415a(10) =-1363409a(11) =92652011a(12) =-651996311a(13) =-10663181255a(14) =262674487895a(15) =-529402905149