For any prime $p$, let $f(p)$ be the least integer such that $f(p)!+1\equiv 0\pmod{p}$.
Is it true that there are infinitely many $p$ for which $f(p)=p-1$?
Is it true that $f(p)/p\to 0$ for almost all $p$?
This page was last edited 04 October 2025.
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