G.f.: Product_{i>0} 1/(Sum_{j>=0} j!*x^(j*i)).

Terms

a(0) =1a(1) =-1a(2) =-2a(3) =-3a(4) =-13a(5) =-65a(6) =-447a(7) =-3351a(8) =-28544a(9) =-269270a(10) =-2795872a(11) =-31689198a(12) =-389581679a(13) =-5165672203a(14) =-73512910689