Thread: 3, 7, 31, 127
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Old 2019-04-03, 17:52   #5
petrw1
1976 Toyota Corona years forever!
 
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"Wayne"
Nov 2006
Saskatchewan, Canada

129D16 Posts
Default I thought this was too easy

The only 4 numbers so far that are:
- exponents of MPs
- an MP

7 for example:

2^3-1 = 7
and
2^7-1 = 31

The next candidate may be a few years away:
(TEX wasn't behaving here)

231 = 2147483647
22147483647 -1 = xxx

Is xxx a prime?
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