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Old 2012-04-02, 09:03   #8
princeps
 
Nov 2011

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Quote:
Originally Posted by literka View Post
I started to read this link and I am totally confused. On the page 2 there is equality
2(Fn-1)/2 = 1 (mod Fn)
where Fn denotes Fermat number.
Take n=1. Then
Fn=F1=5,
(Fn-1)/2 = 2, 2^2=4 and
4 is not equal 1 modulo 5.
Am I missing something?
Yes , you have missed condition : n \geq 2
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