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

Terms

a(0) =1a(1) =1a(2) =5a(3) =25a(4) =169a(5) =1361a(6) =12781a(7) =136585a(8) =1633745a(9) =21594529a(10) =312239701a(11) =4898379641a(12) =82810239865