E.g.f.: Product_{k>0} (1-x^k/k)^k.

Terms

a(0) =1a(1) =-1a(2) =-2a(3) =0a(4) =6a(5) =90a(6) =240a(7) =2100a(8) =1680a(9) =-28560a(10) =-682080a(11) =-7835520a(12) =-134497440a(13) =-1059458400a(14) =-13047914880a(15) =-138646347840