Shortest math paper ever published [Conway and Soifer, 2004]

Here's a really interesting writeup by one of the authors explaining the history and context behind this paper: http://www.wfnmc.org/mc20101.pdf

Apparently the question posed in the title of the paper is still an open question, although both authors conjecture that the answer is "no".

previous discussion on HN (2015): https://news.ycombinator.com/item?id=10622660

Other candidates for "shortest math paper ever": https://hsm.stackexchange.com/a/14612/18150