I recently put in ~30k WU's to Sophie Germain (around 220k credit) - and did not find any primes.

I've also been watching the subproject status for SG - and like me, it also appears no one else is finding any SG primes... for quite some time

I'd like to understand the SG subproject status page. Why is it for n=666666 there are so many more tasks being run? Based on the same page, other values of n are finding more primes with far fewer tasks.

For example, looking at the SG subproject status page, the probability of finding a prime for n=666666 is 0.0015%, where for other values of n it averages around 0.015% - an order of magnitude better!

I guess it would help if someone could explain:
* how the k and n values are chosen
* why n=666666 is running with a much bigger k range than other values of n
* SG primes are of the form p and 2p+1. What do k and n mean in the p and 2p+1 equation?
* when we SG move to a different n? Seems like n=666666 is pretty dry of primes.


Any thoughts here? Thanks.

Ok, it's really only n=666666, but even k are included. So something_even*2^666666-1 becomes half_of_something_even*2^666667-1 and so on. That's why half of the n's are 666,666 (odd k). 1/4 of the n are 666,667 (k multiply of 2), 1/8 are 666,668 (k multiple of 4), and so on.

That should answer Q1 and Q2.

Q3: If p=k*2^n-1 then 2*p+1=2*(k*2^n-1)+1=2k*2^n-2+1= k*2^(n+1)-1
So if we find 2 consecutive n values with the same k prime. We found the Sophie Germain.

Q4: I don't know, why 666,666 has the fewest primes although having the most tests. Could be a coincidence or is for a reason the next person will share with us ;)

but who picked n=666666 anyway.

according to the main thread and wikipedia (and other places)
there are already a large number of SG primes knowns.

ie from wikipedia

The first few Sophie Germain primes are:
2, 3, 5, 11, 23, 29, 41, 53, 83, 89, 113, 131, 173, 179, 191, 233, …... (sequence A005384 in OEIS).
The largest known Sophie Germain prime as of March 2010 is 183027 × 2265440−1.

It took me a couple minutes, but I understand what thommy3 is saying. Thanks.

While the mystery has been reduced, some mystery remains.

Clearly half of the the n=666666 SG's have odd k's. So why are the odd k's producing so few primes? Clearly the even k's did much better.

Maybe this is a behavior specific so SG primes?

Is there a prime distribution function for SG primes that can validate Primegrid's findings for n=666666?

Just wondering.

And to shoelace's point, how are k and n values chosen? Are they chosen by Primegrid admin's? Or is PG deterministically working through k's and n's that have yet to be tested?

When will a new n be chosen? When all k's are exhausted for the chosen k? Because, oddly, referring to SG subproject status, the "k max in progress" is larger than the "k max complete". Does that mean the k's have exceeded the range chosen? If so, maybe it's time for a new n.

I was noticing the lack of SGS primes as well...not sure why it's been so quiet. As for the choice of n=666666, my guess is that the folks in charge wanted the n value to be high enough to maintain top 5000 finds for some time and also be low enough to process a significant amount of WUs to try and give the project a better shot at finding the SG prime, and so just decided to double up the value used for the old TPS search (which was n=333333). I don't think there was anything else particularly significant to the choice, but I could be wrong...
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so if we accept that logic.. that it is twice 333333 for TPS.

why did tps pick 333333?

so if we accept that logic.. that it is twice 333333 for TPS.

why did tps pick 333333?

I really would be interested to know why it's been so long since SGS discovered a prime. They used to pop up quite regularly, but now we've been stuck on #244 for quite some time.
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This is great news! I was worried that the primes were starting to dry up in this project...

Roughly 50 new primes to come out in the next few days, nice:) I crunched quite a bit of SGS during the dry spell so I like my odds for one!

Cheers!
Alan
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Looks like I may have just done the deed - or perhaps I am a confirmer - or maybe there's another explanation. No notifications have been received, but my count of primes found for Sophie Germain has inexplicably gone from zero to one today......

Dang, the suspense is killing me!!!!
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First, congrats on getting a hit. Second, I was just informed the SG confirmations are just a tad behind (see post on missing SGS primes). And third, yes not knowing does add a lot of suspense especially if it's your first one.

Regardless congrats again and hopefully you are the prime finding owner :)
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@AggieThePew

Looks like I may have just done the deed!

First, congrats on getting a hit. Second, I was just informed the SG confirmations are just a tad behind (see post on missing SGS primes). And third, yes not knowing does add a lot of suspense especially if it's your first one.

Regardless congrats again and hopefully you are the prime finding owner :)

Just read that thread - wow, quite a backlog: 90 SGS)!!!!

Still, what will happen will happen; I can't change what has gone before. Irrespective of what my participation turns out to be, I'll just carry on chugging away, which after all is my function in all of this!
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Nice to hear that primes are being found on SGS. Like you I am hanging in my suspenders waiting to find out if I am the finder or confirmer to 2 primes that popped up unexpectedly about 4 days ago.

I am so excited as they are my first that I am checking to see what the result is almost every hour Lol. :)
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The art of flying is throwing yourself at the ground and missing.

Well, good and bad news for me:

Dear Primefinder,

Congratulations! Our records indicate that a computer registered by you has
found a unique prime number. This computer is running BOINC, is attached to
the PrimeGrid project, and is assigned to the Sophie Germain Prime Search. What makes
this prime unique is that it's large enough to enter the Top 5000 List in Chris Caldwell's
The Largest Known Primes Database.

Since you have auto-reporting selected, the following prime was submitted on your
behalf:

Added 97033 : 6130676192025*2^666667-1 (200700 digits)

If you have any questions or concerns, please contact me and we will surely resolve any
problem.

Once again, congratulations on your find. Thank you for participating in PrimeGrid.

John Blazek of PrimeGrid

Congrats on your prime.. now for a few anyway your name will be in lights on the main page. I'm still waiting to hear about my one remaining hit.

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@AggieThePew

Congrats on your prime.. now for a few anyway your name will be in lights on the main page. I'm still waiting to hear about my one remaining hit.

Grats on being on the front page Area 51

Still waiting to find out if I am primary finder or validation for the 2 that have shown up on my efforts. :)) Hoping that I am primary finder for both
____________
The art of flying is throwing yourself at the ground and missing.

Congrats on your prime.. now for a few anyway your name will be in lights on the main page. I'm still waiting to hear about my one remaining hit.

.ahhh, my moment of fame has almost gone - last in the list atm. I take it you have no news yet?

A fair number of the 'Newly reported primes' on the front page are Sophies, so perhaps they are starting to clear the backlog. However in the end - if you found it you found it - that won't change however long it takes.

I considered going through tasks and trying to find the requisite one, but decided it really wasn't worth the time and although I'm pretty new to this prime game, I absolutely can understand the 'wanting to know' feeling! I even considered writing a PERL script to page scrape my tasks and find the blighter - but then thought that's not fair on the servers!!!!!

Perhaps Santa will come early for you (like tomorrow)!
____________

A fair number of the 'Newly reported primes' on the front page are Sophies, so perhaps they are starting to clear the backlog. However in the end - if you found it you found it - that won't change however long it takes.

I considered going through tasks and trying to find the requisite one, but decided it really wasn't worth the time and although I'm pretty new to this prime game, I absolutely can understand the 'wanting to know' feeling! I even considered writing a PERL script to page scrape my tasks and find the blighter - but then thought that's not fair on the servers!!!!!

Perhaps Santa will come early for you (like tomorrow)!

Yippe One is confirmed as finder and the other double checker :)

Entrance number in the top 5000 DB 2582

Dear Primefinder,


Congratulations! Our records indicate that a computer registered by you has
found a unique prime number. This computer is running BOINC, is attached to
the PrimeGrid project, and is assigned to the Sophie Germain Prime Search. What makes
this prime unique is that it's large enough to enter the Top 5000 List in Chris Caldwell's
The Largest Known Primes Database.

Since you have auto-reporting selected, the following prime was submitted on your
behalf:

Added 97098 : 6081793616325*2^666667-1 (200700 digits)

If you have any questions or concerns, please contact me and we will surely resolve any
problem.

Once again, congratulations on your find. Thank you for participating in PrimeGrid.

John Blazek of PrimeGrid

____________
The art of flying is throwing yourself at the ground and missing.

Yippe One is confirmed as finder and the other double checker :)

Entrance number in the top 5000 DB 2582

Dear Primefinder,


Congratulations! Our records indicate that a computer registered by you has
found a unique prime number. This computer is running BOINC, is attached to
the PrimeGrid project, and is assigned to the Sophie Germain Prime Search. What makes
this prime unique is that it's large enough to enter the Top 5000 List in Chris Caldwell's
The Largest Known Primes Database.

Since you have auto-reporting selected, the following prime was submitted on your
behalf:

Added 97098 : 6081793616325*2^666667-1 (200700 digits)

If you have any questions or concerns, please contact me and we will surely resolve any
problem.

Once again, congratulations on your find. Thank you for participating in PrimeGrid.

John Blazek of PrimeGrid

Just wondering if validation for SG primes are still backlogged...can anyone cofirm or is it just a longer process with SGP's? I've had 8 hits with only one confirm...two are fairly recent but the other 5 popped up a while back...probably more than a month and a half ago.

Ignore that previous post...it was answered in another thread. I also found the edit button, which was staring me in the face. :)

Cheers...