most recent 30 from http://mathoverflow.net 2013-05-18T13:43:37Z http://mathoverflow.net/feeds/question/105834 http://www.creativecommons.org/licenses/by-nc/2.5/rdf http://mathoverflow.net/questions/105834/reference-request User1257 2012-08-29T13:37:07Z 2012-10-13T15:37:00Z

<p>I am looking for a reference or proof for the following problem:</p> <p>Problem: Let $r$ be prime, then $2r$ is a Sylow $p$-number if and only if $2r=1+p^{2^n}$. Thanks in advance.</p>