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

Terms

a(0) =1a(1) =0a(2) =4a(3) =6a(4) =64a(5) =300a(6) =2568a(7) =20160a(8) =193856a(9) =1989792a(10) =22687200a(11) =279956160a(12) =3737966208a(13) =53589444480a(14) =821522026752