Expansion of e.g.f.: exp(exp(-x) - 1).

Terms

a(0) =1a(1) =-1a(2) =2a(3) =-5a(4) =15a(5) =-52a(6) =203a(7) =-877a(8) =4140a(9) =-21147a(10) =115975a(11) =-678570a(12) =4213597a(13) =-27644437a(14) =190899322a(15) =-1382958545a(16) =10480142147a(17) =-82864869804a(18) =682076806159