It is easy to see that 2
p-1 is prime iff p is prime... I'm not sure its really easy at all... maybe I'll wait for the proof to come up on the [Prime numbers]
?s page; but in the mean time, the sentence should be reworded for a regular guy (like me) to know whats going on. --cM
Ok, I'll reword it. In fact, "iff" is wrong.
If 2
p-1 is prime,
then p must itself be prime.
--Axel
"Iff" being the abbreviation used in logic for "if and only if"?
Yes.
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