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

Terms

a(0) =1a(1) =1a(2) =1a(3) =3a(4) =15a(5) =75a(6) =435a(7) =3045a(8) =24465a(9) =220185a(10) =2200905a(11) =24209955a(12) =290529855a(13) =3776888115a(14) =52876298475a(15) =793144477125