E.g.f.: exp(x)/sqrt(1-x^2).

Terms

a(0) =1a(1) =1a(2) =2a(3) =4a(4) =16a(5) =56a(6) =376a(7) =1912a(8) =17984a(9) =119296a(10) =1438336a(11) =11749376a(12) =172665472a(13) =1674715264a(14) =29022277376a(15) =325841353216