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-   -   Sierpinski/Riesel Base 5: Post Primes Here (https://www.mersenneforum.org/showthread.php?t=3125)

 geoff 2005-01-25 22:11

Robert, could you make available a list of the primes you found for n <= 18468? Or if you email it to me ( geoff AT hisplace DOT co DOT nz ) I will make it available.

I will keep a list of primes that make the top 5000 list in [url]http://www.geocities.com/g_w_reynolds/Sierpinski5/champs.txt[/url], there is just one entry so far.

My results: I found (a while ago) that 32518*5^47330+1 is prime.
I am reserving these k: 10918, 12988, 31712.

 michaf 2005-01-28 06:31

Hello all,

I agree with uncwilly that this project should deserve it's
own private place... anyone know how to move it?

In the meantime:

One more down:

PFGW Version 20041020.Win_Stable (v1.2 RC1c) [FFT v23.8]

Primality testing 42004*5^27992+1 [N-1, Brillhart-Lehmer-Selfridge]
Running N-1 test using base 2
Calling Brillhart-Lehmer-Selfridge with factored part 99.98%
42004*5^27992+1 is prime! (57.0569s+0.0044s)

 michaf 2005-01-30 12:42

Yet another one down

Hi all,

4th prime on here:

PFGW Version 20041020.Win_Stable (v1.2 RC1c) [FFT v23.8]

Primality testing 44134*5^39614+1 [N-1, Brillhart-Lehmer-Selfridge]
Running N-1 test using base 7
Calling Brillhart-Lehmer-Selfridge with factored part 99.98%
44134*5^39614+1 is prime! (150.2650s+0.0062s)

Cheers, Micha

 ltd 2005-01-31 20:28

Hi,

60124*5^38286+1 is prime!

60394 tested to 50166 ( i keep this reserved)
60722 tested to 49329 ( i keep this reserved)

I also keep my other k reserved.

Lars

 geoff 2005-02-01 02:13

The primes.txt file in [url]http://www.geocities.com/g_w_reynolds/Sierpinski5/[/url] contains the k,n pairs for all the primes k*5^n+1 found so far. It can be used as input to Proth.exe in file mode, or by adding 'ABC \$a*5^\$b+1' to the top, as input to pfgw.

 robert44444uk 2005-02-01 18:01

Nought

This may come to nought, actually no, it will come to k+1

What am I talking about? n=0 ---> k*5^0+1= k+1

Therefore any k still remaining where k+1 is prime can be eliminated, unless that is not in the Sierpinski rule book. Looking at my original list, this would eliminate 7528 and maybe others....not got a list of primes to hand

What does this group think of this wheeze?

Regards

Robert Smith

 robert44444uk 2005-02-01 21:09

n=0

Following on, now I am home:

From the original list n=0 eliminates (and a number of these we have found already higher primes or prp for):

7528
15802
33358
43018
51460
81700
82486
90676
102196
105166
123406
123910
143092
152836
159706

Regards

Robert Smith

 geoff 2005-02-01 22:35

[QUOTE=robert44444uk]Therefore any k still remaining where k+1 is prime can be eliminated, unless that is not in the Sierpinski rule book.[/QUOTE]
The definitions of Sierpinski number that I have seen take n to be positive, e.g. [url]http://mathworld.wolfram.com/SierpinskisCompositeNumberTheorem.html[/url], so I think we should leave these k in the list. (If they turn out to be harder than the other k then we could reconsider :-)

 pcco74 2005-02-02 14:01

[QUOTE=geoff]The definitions of Sierpinski number that I have seen take n to be positive, e.g. [url]http://mathworld.wolfram.com/SierpinskisCompositeNumberTheorem.html[/url], so I think we should leave these k in the list. (If they turn out to be harder than the other k then we could reconsider :-)[/QUOTE]
Yves Gallot's site also lists n as having to be greater than or equal to one. [url]http://www.prothsearch.net/sierp.html[/url]

 Citrix 2005-02-02 18:10

[QUOTE=pcco74]Yves Gallot's site also lists n as having to be greater than or equal to one. [url]http://www.prothsearch.net/sierp.html[/url][/QUOTE]

This is for base 2 only, 5^0 should be considered too.

 robert44444uk 2005-02-02 19:10

Odds and evens

I posted the following message on Yahoo primenumbers to see whether one of the maths bods can give an answer. I am reasonably confident we should allow n=0