E.g.f.: Product_{k>=1} 1/(1 + x^k/k).

Terms

a(0) =1a(1) =-1a(2) =1a(3) =-5a(4) =20a(5) =-104a(6) =584a(7) =-4304a(8) =35720a(9) =-329160a(10) =3239112a(11) =-36135912a(12) =438454752a(13) =-5743527360a(14) =80351263680