Question 69
Let $n \ge 2$, be an integer. Find in terms of $n$ the maximum value of $m \le n$ such that we can select $m$ numbers from the set $1, 2, 3, \dots, n$ in such a way that for any two of them, say $a, b$, with $a \gt b$, the number $a-b$ does not divide $a+b$.
Vasile Pop
Vasile Pop