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Old 2017-08-05, 15:58   #1838
VBCurtis
 
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"Curtis"
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Quote:
Originally Posted by paulunderwood View Post
Hrmm. Both were found by the same machine, a new low-end i3 desktop that hasn't had its case opened. Thanks for pointing this out- I'll run a double-check on another machine myself, as the compositeness test you linked indicated some roundoff errors.
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Old 2017-08-05, 17:02   #1839
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A double-check on my i7-haswell (linux-sllr64) confirms compositeness. Next time I see the machine that found this "prime", I'll make sure I didn't transpose digits when I copied down the exponent; but that's pretty unlikely with 3 consecutive zeros.
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Old 2017-08-06, 07:53   #1840
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1423*2^2179023-1

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Since we are on the subject of consecutive large primes with small n gaps, here is a pair I found a while back:

1423*2^2179023-1
1423*2^2178363-1

The most interesting thing about this pair is that the k value has very low nash weight of just 309.

It would be interesting if we could define a function that takes in the gap size, nash weight, and n size and outputs another number representing the "rarity" of the pair.
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Old 2017-09-18, 09:42   #1841
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49*2^4360869-1 (1312755 digits)
49*2^4365175-1 (1314051 digits)
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Old 2017-09-18, 09:52   #1842
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Quote:
Originally Posted by amphoria View Post
49*2^4360869-1 (1312755 digits)
49*2^4365175-1 (1314051 digits)
Congratulations on this very nice pair, Dave!
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Old 2017-09-20, 09:04   #1843
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Hi Dave, Congrats on nice primes!

Congrats also to Trilo on his pair.
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Old 2017-12-13, 20:19   #1844
Chair Zhuang
 
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How long did your computer take to test it? And how many GHz has your computer?
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Old 2017-12-14, 14:48   #1845
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Quote:
Originally Posted by Chair Zhuang View Post
How long did your computer take to test it? And how many GHz has your computer?
The first took 6300s to test on a 3.6 GHz Ivy Bridge CPU. The second was tested on a 2.9 GHz Haswell CPU. I currently don't have access to the timing but given that it has AVX2, I would expect it to be at least as fast as the other despite the lower clock speed.
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Old 2017-12-15, 22:58   #1846
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Thank you! amphoria. I am a new member.
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Old 2017-12-18, 22:22   #1847
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229*22581111-1 is prime. 776995 digits.
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Old 2017-12-30, 10:40   #1848
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From our 7th drive:
2715*2^1629931-1 (490662 digits)
2715*2^1640137-1 (493734 digits)
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