Expansion of e.g.f. (1 - x^2)^(-x).

Terms

a(0) =1a(1) =0a(2) =0a(3) =6a(4) =0a(5) =60a(6) =360a(7) =1680a(8) =20160a(9) =151200a(10) =1663200a(11) =17962560a(12) =219542400a(13) =2854051200a(14) =40441040640a(15) =606356150400