RMO 2024 Problem 2

For a positive integer $n$ , let $R(n)$ be the sum of the remainders when $n$ is divided by $1,2, \cdots , n$ . For example, $R(4) = 0 + 0 + 1 + 0 = 1,$ $R(7) = 0 + 1 + 1 + 3 + 2 + 1 + 0 = 8$ . Find all positive integers such that $R(n) = n-1$ .