MathDB
A 55

Source:

May 25, 2007
Divisibility Theory

Problem Statement

Show that for every natural number nn the product (421)(422)(423)(42n)\left( 4-\frac{2}{1}\right) \left( 4-\frac{2}{2}\right) \left( 4-\frac{2}{3}\right) \cdots \left( 4-\frac{2}{n}\right) is an integer.