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

Terms

a(0) =0a(1) =0a(2) =2a(3) =15a(4) =112a(5) =925a(6) =8556a(7) =88249a(8) =1007056a(9) =12612681a(10) =172092340a(11) =2541367741a(12) =40385290584a(13) =687120886621