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Given a prime number $p>2$ and a finite set of primes $l_1,...,l_n$ (different from $p$). By Fermat's little theorem, we know that $l_1 | (p^{l_1-1}-1)$, so my questions are:

  1. Is there an integer $r$ such that $l_i | (p^r-1)$ for all $i=1,...,n$?
  2. Is there an integer $r$ such that $l_i \nmid (p^r-1)$ for all $i=1,...,n$?
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    Love your use of $l$ as a variable. Deliciously confusing! Mwahahahahahahahahahaha!2017-02-08

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  1. Yes, $r=\prod_{i=1}^n (l_i-1)$.
  2. Not in general: if $l\mid (p-1)$, then $l\mid (p^r-1)$ for all $r\in \Bbb N$.