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#1 |
Account Deleted
"Tim Sorbera"
Aug 2006
San Antonio, TX USA
17×251 Posts |
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Has anybody tried taking a list of primes from the top 5000, or other lists of primes, and searching the opposite side for a prime? (e.g. #500 is currently 2951*2^852818-1, so sieve and if necessary LLR 2951*2^852818+1; in this case it has small factors, just an example) It could potentially be a very easy way to find a twin prime pair where one side is already known.
Last fiddled with by Mini-Geek on 2009-10-20 at 13:54 |
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#2 |
I quite division it
"Chris"
Feb 2005
England
31×67 Posts |
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I tried that a couple of years ago and got part way through the list. (From the bottom up.)
edit: Check out the "Other Primes" thread at NPLB, from post 20. Last fiddled with by Flatlander on 2009-10-20 at 16:08 |
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#3 |
Jan 2009
Ireland
2·3·31 Posts |
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thought of this earlier in the year,but came to the conclusion that someone would of done this already.thought it would be logical for someone that's searching for a twin prime to test the opposite side of known primes.
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#4 | |||
Account Deleted
"Tim Sorbera"
Aug 2006
San Antonio, TX USA
17×251 Posts |
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#5 |
I quite division it
"Chris"
Feb 2005
England
207710 Posts |
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I'mm 99% sure anything I tested would be off the list now. I think it was longer than 2 years ago; I don't think I got near k*2^400000-1.
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#6 |
Dec 2006
Anchorage, Alaska
2×3×13 Posts |
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You might also go to the -3 and not just the opposite side?
ie 253*2^5000-1 and 253*2^5000-3 or some such thing Still a twin! |
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#7 |
Jul 2009
22 Posts |
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The problem with the -3 is I don't think there's an easy primality test for k2^n-3. That's why all our searches are for +1 and -1 is people have figured out "easy" tests to show whether those are prime. For numbers of random form the best we can do is show it's probably prime.
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#8 |
Sep 2004
13×41 Posts |
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The ones on the list are way to big for primo as well. It still would be an interesting project to show they are prp's though.
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#9 | |
May 2004
New York City
102108 Posts |
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I have an idea, but it's just germinating. |
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