MathDB
b is integer if a is integer, 2a + a^2= 2b + b^2 (2021 Polish JMO R2 p1)

Source:

April 8, 2021
number theoryInteger

Problem Statement

The numbers a,ba, b satisfy the condition 2a+a2=2b+b22a + a^2= 2b + b^2. Prove that if aa is an integer, bb is also an integer.