Expansion of e.g.f. exp(-x)/(1-2*x).

Terms

a(0) =1a(1) =1a(2) =5a(3) =29a(4) =233a(5) =2329a(6) =27949a(7) =391285a(8) =6260561a(9) =112690097a(10) =2253801941a(11) =49583642701