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Claim. The statement of Problem 398, that $n=4,5,7$ are the only solutions of $n!=x^2-1$. S. Cerdá, The Brocard-Ramanujan's Diophantine Equation $n!+1=m^2$, arXiv:1504.06694, first posted 25 April 2015, presents, as its abstract says, a method to find the solutions of the equation, and the comment on its arXiv record says that the problem was solved by modular congruence techniques. The page is dated by the first posting.

Standing. Withdrawn. The arXiv record shows five versions: versions 1 and 2 of April 2015; version 3 of 30 April 2015, withdrawn; version 4 of 18 February 2016, a new version of the paper, whose comment records that the earlier one had been withdrawn because a reviewer found a logical fallacy; and version 5 of 2 March 2016, again withdrawn, with the comment that the solution contains a mistake. No version was published, the manuscript was never posted to the site, and no later claim by the author is known here. The problem's standing takes nothing from this page.

Depends on. No page of this wiki.