Copyright © University of Cambridge. All rights reserved.

'Square Product' printed from http://nrich.maths.org/

Show menu


What is the smallest integer $n$ such that the product $$(2^2 -1)(3^2 -1)(4^2 -1)...(n^2 -1)$$is a perfect square?
 
 
If you liked this problem, here is an NRICH task which challenges you to use similar mathematical ideas.

 

See all short problems arranged by curriculum topic in the short problems collection
This problem is taken from the UKMT Mathematical Challenges.