View source for Smarandache function

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Given a natural number $n$, the value of the Smarandache function $ \eta $ at $n$ is the smallest natural number $m$ such that $n$ divides $m!$. An elementary observation is that $\eta ( n ) \leq n$, and that $\eta ( n ) = n$ if and only if $n$ is a prime number or equal to $4$.

====References====
<table><tr><td valign="top">[a1]</td> <td valign="top">  F. Smarandache,   "A function in number theory"  ''Smarandache Function J.'' , '''1'''  (1990)  pp. 3–65</td></tr></table>