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Old 2019-11-23, 22:25   #5
a1call
 
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"Rashid Naimi"
Oct 2015
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The Mersenne part has been known since 1775 as proven in this link first shown to me by sm:
https://primes.utm.edu/notes/proofs/MerDiv2.html
It is of practical use in proving factors of Mersenne numbers with prime exponents prime.
23 is guaranteed to be prime because it divides M11 and 23= 2*11+1

Last fiddled with by a1call on 2019-11-23 at 22:26
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