E.g.f.: x/(x+3-2*exp(x)).

Terms

a(0) =0a(1) =1a(2) =2a(3) =12a(4) =80a(5) =690a(6) =7092a(7) =85162a(8) =1168400a(9) =18034938a(10) =309307340a(11) =5835250410a(12) =120092842872