a(n) = (-1)^(n+1) * 2^n * n!^2.

A055546

a(n) = (-1)^(n+1) * 2^n * n!^2.

Terms

    a(0) =-1a(1) =2a(2) =-16a(3) =288a(4) =-9216a(5) =460800a(6) =-33177600a(7) =3251404800a(8) =-416179814400

External references