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\title{Arithmetic progressions and relative primes}
\author{Jos\'e Manuel Rodr\'iguez Caballero}
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\begin{abstract}
This article provides a formalization of the solution obtained by the author of the Problem ``ARITHMETIC PROGRESSIONS" from the 
Putnam exam problems \cite{putnam} of $2002$. The statement of the problem is as follows: For which integers $n>1$ does the set of positive integers less than and relatively prime to $n$ constitute an arithmetic progression?
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