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Old 2019-01-06, 20:17   #6
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"Forget I exist"
Jul 2009

26·131 Posts

Originally Posted by Blackadder View Post
Is that rhetorical? I really should get back into my math books.

Special as in: why are we calculating for 2p-1 and not 2p-2 as well. I guess the latter can't be prime?
no number divisible by a number other than 1 or itself is prime 2p-2 = 2(2p-1-1) therefore is divisible by 2 except when p-1 = 1 and therefore p=2 -- 2p-1-1 = 1

Last fiddled with by science_man_88 on 2019-01-06 at 20:18
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