a(0)=1, a(n)=n*(a(n-1)-2).

Terms

a(0) =1a(1) =-1a(2) =-6a(3) =-24a(4) =-104a(5) =-530a(6) =-3192a(7) =-22358a(8) =-178880a(9) =-1609938a(10) =-16099400a(11) =-177093422a(12) =-2125121088a(13) =-27626574170a(14) =-386772038408