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

Terms

a(0) =1a(1) =0a(2) =0a(3) =3a(4) =0a(5) =15a(6) =90a(7) =210a(8) =2520a(9) =13230a(10) =103950a(11) =873180a(12) =7484400a(13) =72972900a(14) =745404660a(15) =8185126950a(16) =95805309600