4n + 1 and 9n + 1 are perfect squares
Source: 9th QEDMO p1 Juniors (21-22. 9. 2011) https://artofproblemsolving.com/community/c1512515_qedmo_200507
May 15, 2021
number theoryPerfect Square
Problem Statement
Find all integers for which both and are perfect squares.