In my other question two days ago I asked for confirmation, whether one step of an attempt to that problem
does there exist $k,n>2$ , such that $\sum_{j=1}^k j^n = (k+1)^n $ ?
was justified. I had fiddled with that problem some years ago (2006/2007) and attributed this problem to Paul Erdős since - I think because of some informal comment of some discutant whom I took as authority (so I missed the point to track this down to a source at that time of exploration...).
After some search in my own text-sources and now googling for online sources I don't find any useful hint for the authorship of this problem.
Could someone kindly provide a reference or a hint for that problem/context and its author?