  Erd\H{o}s, Graham, and Selfridge considered, for each positive integer $n$,
the least value of $t_n$ so that the integers $n+1, n+2, \dots, n+t_n $ contain
a subset the product of whose members with $n$ is a square. An open problem
posed by Granville concerns the size of $t_n$, under the assumption of the ABC
Conjecture. We establish some results on the distribution of $t_n$, and in the
process solve Granville's problem unconditionally.
