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pow:problem4f22 [2022/10/29 01:39] mazurpow:problem4f22 [2022/10/29 01:40] (current) mazur
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 +<box 85% round orange| Problem 4 (due on Monday, October 24)>
  
 +A sequence $(a_n)$ of positive integers has been created using the following process: 
 +\[ a_{n+1}=a_n+3\frac{a_n}{p_n}\]
 +where $p_n$ is a prime divisor of $a_n$. Prove that there is a positive integer $k$ such that the equality
 +$a_{n+k}=2ka_n$ holds for infinitely many values of $n$.  
 +
 +</box>
 +
 +We received a solution from Garrett Gramzow, Prof. Vladislav Kargin, and Ashton Keith. All three
 +solutions as well as our original solution are essentially following the same line of argument,
 +though Garrett's solution needs some improvements in exposition. It turns out that
 +either $k=1$ or $k=2$ works. For a detailed solution see the following link {{:pow:2022fproblem4.pdf|Solution}}.