20170722, 09:08  #1 
Nov 2016
29 Posts 
Do 2^p1 numbers ever have the same first prime factor?
Looking at the small sample from http://oeis.org/A136030  Smallest prime factor of composite Mersenne numbers:
[23, 47, 233, 223, 13367, 431, 2351, 6361, 179951, 193707721, 228479, 439, 2687, 167, 11447, 7432339208719, 2550183799, 745988807, 3391, 263, 32032215596496435569, 5625767248687, 86656268566282183151, 18121, 852133201, 150287, 2349023, 730753, 359, 43441, 383] There are no duplicates here, but I have not checked further. I tried looking on http://factordb.com/ but I can't work out how to get it to only list the factors of 2^p1 numbers  I couldn't exclude non prime odd exponents. Are there any examples of shared first prime factors? 
20170722, 11:20  #2  
"Forget I exist"
Jul 2009
Dumbassville
20D0_{16} Posts 
Quote:


20170722, 11:26  #3 
Nov 2016
1D_{16} Posts 

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