Math Forum :: View topic – Number theory( factorial ) 2월 13, 2005 admin Number theory( factorial ) Author Message Edward Joined: 02 Dec 2004Posts: 2 Posted: Thu Dec 02, 2004 4:48 pm Post subject: Number theory( factorial ) Let Find all such that is a square number. Soarer Frequent VisitorJoined: 18 Jan 2004Posts: 181 Location: Hong Kong Posted: Thu Dec 02, 2004 5:42 pm Post subject: For n>=5, A(n)=4!+3!+2!+1=3(mod 5) Since 3 is quadratic nonresidue, n