MathDB
Fractions and reciprocals

Source: 2013 BAMO-8 #4

February 27, 2016
algebra

Problem Statement

For a positive integer n>2n>2, consider the n1n-1 fractions 21,32,,nn1\dfrac21, \dfrac32, \cdots, \dfrac{n}{n-1} The product of these fractions equals nn, but if you reciprocate (i.e. turn upside down) some of the fractions, the product will change. Can you make the product equal 1? Find all values of nn for which this is possible and prove that you have found them all.