Question 18
The first $n$ positive integers are written on a board ($n \ge 3$). Ante repeats the following procedure: first he chooses two numbers on the board, and then he increases them both by the same arbitrary positive integer.
Determine all positive integers $n$ such that Ante can, by repeating this procedure, achieve that all numbers on the board are equal. (Ilko Brnetić)
Determine all positive integers $n$ such that Ante can, by repeating this procedure, achieve that all numbers on the board are equal. (Ilko Brnetić)