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Old 2007-01-10, 16:27   #3
fatphil
 
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May 2003

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Quote:
Originally Posted by CedricVonck View Post
n = 22 tested to 144895
Containing
<<<
22*22^511+1 is not prime.
22*22^2047+1 is not prime.
22*22^3583+1 is not prime.
22*22^6655+1 is not prime.
>>>

Are you sure you know what you're doing?
Those are 22^n+1, which can only ever be prime if n=2^m for some n, namely generalised Fermat numbers.
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