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#1 |
"Angelino Desmet"
Mar 2018
Belgium
2E16 Posts |
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Why is 2p-1 special, and not 2p-2?
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#2 |
Banned
"Luigi"
Aug 2002
Team Italia
26×3×52 Posts |
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#3 |
"Serge"
Mar 2008
Phi(4,2^7658614+1)/2
22·32·7·37 Posts |
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In what sense special?
2p-2 is special in its own way, too |
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#4 |
"Forget I exist"
Jul 2009
Dumbassville
20C016 Posts |
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#5 |
"Angelino Desmet"
Mar 2018
Belgium
2×23 Posts |
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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? Last fiddled with by Blackadder on 2019-01-06 at 20:02 |
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#6 |
"Forget I exist"
Jul 2009
Dumbassville
26×131 Posts |
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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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#7 |
"Angelino Desmet"
Mar 2018
Belgium
2×23 Posts |
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#8 |
"Serge"
Mar 2008
Phi(4,2^7658614+1)/2
100100011011002 Posts |
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