Question 1
(BEL), IMO 4. (a) For which values of $n>2$ is there a set of $n$ consecutive positive integers such that the largest number in the set is a divisor of the least common multiple of the remaining $n-1$ numbers?
(b) For which values of $n>2$ is there a unique set having the stated property?
(b) For which values of $n>2$ is there a unique set having the stated property?