Duplicate of A071543.

Terms

a(0) =1a(1) =3a(2) =-4a(3) =12a(4) =144a(5) =576a(6) =-7104a(7) =45248a(8) =450432a(9) =2240512a(10) =5292544a(11) =-88076288a(12) =-62210048