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Old 2020-09-13, 02:05   #5
CRGreathouse's Avatar
Aug 2006

2×2,969 Posts

Originally Posted by bhelmes View Post
If f | Mp and p is prime then

a) f | 2n²-1

b) but not f=2n²-1

a) is clear for me but b) is a guess (I checked some numbers)

The first and fastest counterexample is welcome (Or a proof ?)
2*2^2-1 | 2^3-1
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