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Message boards : The Riesel Problem : k=273809 eliminated!

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Michael Goetz
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Message 112293 - Posted: 13 Dec 2017 | 17:41:21 UTC

Congratulations to DeleteNull for finding the 2.6 million digit mega-prime 273809*2^8932416-1 and eliminating k=273809 from the Riesel Problem! 49 k's remain.

This is PrimeGrid's 60th mega prime of 2017, our 195th mega prime overall, and the 15th k eliminated by PrimeGrid from The Riesel Problem. This is also DeleteNull's second mega-prime, as well as the second k he's eliminated from one of the our conjecture projects. (Click here for the full list of DeleteNull's prime discoveries at PrimeGrid.)
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My lucky number is 75898524288+1
(I am NOT an administrator anymore, so please don't PM me with questions. I can't help.)

Rafael
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Message 112294 - Posted: 13 Dec 2017 | 18:04:37 UTC

Chaotic Disorder

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Message 112295 - Posted: 13 Dec 2017 | 18:31:44 UTC - in response to Message 112293.

So why does a k get eliminated if a prime is found? Is that the only one that is possible from it?

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JimB
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Message 112296 - Posted: 13 Dec 2017 | 18:35:16 UTC - in response to Message 112295.

So why does a k get eliminated if a prime is found? Is that the only one that is possible from it?

http://www.prothsearch.com/rieselprob.html

or

DeleteNull
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Message 112300 - Posted: 13 Dec 2017 | 20:11:36 UTC - in response to Message 112293.

Congratulations to DeleteNull for finding the 2.6 million digit mega-prime 273809*2^8932416-1 and eliminating k=273809 from the Riesel Problem! 49 k's remain.

Many thanks to all who have helped to make this possible! I am the lucky one who got this special workunit to eleminate that k.

And 49 k remain, so there will be other lucky (and patient) finders in the future ;)
____________
DeleteNull

dukebg
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Message 112315 - Posted: 14 Dec 2017 | 15:29:14 UTC

Congratulations!
That's pretty amazing. More than 3 years since a k was eliminated in TRP last time!

Michael Becker

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Message 112317 - Posted: 14 Dec 2017 | 18:48:56 UTC - in response to Message 112315.

Congratulations!!

Anthony Ayiomamitis

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Message 112318 - Posted: 14 Dec 2017 | 18:56:10 UTC - in response to Message 112317.

My congrats as well.

Eudy Silva

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Message 112319 - Posted: 14 Dec 2017 | 19:04:44 UTC - in response to Message 112318.

Well done !

Rick Reynolds

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Message 112321 - Posted: 14 Dec 2017 | 20:03:58 UTC

Big congrats !

Dave

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Message 112322 - Posted: 14 Dec 2017 | 20:15:03 UTC

Another +1 well done - nice achievement to (nearly) end the year.

Iain Bethune
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Message 112323 - Posted: 14 Dec 2017 | 20:59:25 UTC - in response to Message 112322.

Another +1

Nope, it's a -1 (Riesel), not Proth ;)
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Proud member of team "Aggie The Pew". Go Aggie!
3073428256125*2^1290000-1 is Prime!

JeppeSN

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Message 112327 - Posted: 14 Dec 2017 | 22:11:25 UTC - in response to Message 112323.

Another +1

Nope, it's a -1 (Riesel), not Proth ;)

Ha ha.

But it depends on the perspective. If you write the candidate as:

N = k·2^n - 1

then you are right, we see a minus one.

But if you express instead, in terms of N, the number that is smooth to factor, that is N + 1, so for example in the help for PFGW, you can see:

-t currently performs a deterministic test. By default this is an N-1
test, but N+1 testing may be selected with '-tp'. N-1 or N+1 is
factored, and Pocklington's or Morrison's Theorem is applied. If 33%
size of N prime factors are available, the Brillhart-Lehmer-Selfridge
test is applied for conclusive proof of primality. If less than 33%
is factored, this test provides 'F-strong' probable primality with
respect to the factored part F.

And in Caldwell's Primality Proving pages, the term N+1 test is used in the same sense.

So Riesel is an N+1 test.

+1 to me.

/JeppeSN

vasyannyasha

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Message 112337 - Posted: 15 Dec 2017 | 7:52:31 UTC

4th place in Riesel primes top!
Very nice!
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(252^6548-1)^2-2 is prime! Small, but mine.
134137784^32768+1(DC)
107853608^8192+1(DC)
10465966^16384+1(DC)

Crun-chi
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Message 112338 - Posted: 15 Dec 2017 | 8:16:53 UTC - in response to Message 112337.

That is what I call "the prime" :)

Congratulations!
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314187728^131072+1 GENERALIZED FERMAT :)
93*10^1029523-1 REPDIGIT PRIME
31*332^367560+1 CRUS PRIME
Proud member of team Aggie The Pew. Go Aggie!

Message boards : The Riesel Problem : k=273809 eliminated!