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Problems and Help :
Help with finding primes
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I'm not new to PrimGrid, but never paid all that much attention
But recently I've become really keen to also find some primes. I have found two small ones so far. It appears that the same names come up again and again for people finding primes... is there a tip in finding primes or is it just luck of the draw (and the fact that these people crunch a lot of tasks)?
Just want to check that I'm not missing something here. The tasks that run in Boinc, are they actually searching for primes or am I just validating other people searches.
Any help/clarity will be appreciated ;)  

RafaelVolunteer tester
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Joined: 22 Oct 14 Posts: 899 ID: 370496 Credit: 401,321,144 RAC: 481,926

I'm not new to PrimGrid, but never paid all that much attention
But recently I've become really keen to also find some primes. I have found two small ones so far. It appears that the same names come up again and again for people finding primes... is there a tip in finding primes or is it just luck of the draw (and the fact that these people crunch a lot of tasks)?
Just want to check that I'm not missing something here. The tasks that run in Boinc, are they actually searching for primes or am I just validating other people searches.
Any help/clarity will be appreciated ;)
At the end of the day, luck really is the deciding factor. Bar that, the best you can do is to have A LOT of computing power to improve your odds of being assigned the right lotto ticket; that can be done by either having more machines yourself or renting servers from the cloud to crunch for you. For reference, last challenge we had someone dump over 3k to get additional processing power from Digital Ocean's servers.  


Ok, thanks so much for the answer. Then I can relax ... I was just worried that I'm missing something. Well then I will just keep on crunching ;)
Thanks again.  

Michael GoetzVolunteer moderator Project administrator
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Joined: 21 Jan 10 Posts: 13634 ID: 53948 Credit: 281,155,805 RAC: 20,342

You're not missing anything. Sometimes people just get *really* lucky, the when you see someone's name again and again, it's because they're using a lot of computers.
____________
My lucky number is 75898^{524288}+1  

BurVolunteer tester
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Joined: 25 Feb 20 Posts: 430 ID: 1241833 Credit: 235,448,062 RAC: 960,129

A bit late, but anyway:
If you are set on finding any prime, then SGS (for CPU) and GFN15 (for GPU) are your best bet. You have a 50% chance of finding a prime in SGS within 14000 tasks and my old i3 managed 4 tasks per core and hour. It's not large enough for entry in T5K, but still a large prime you can use to impress girls (or boys).
If you want entry into T5K, PPSE (CPU) and GFN16 (GPU) are the best choice. Lower probability of course. On average it takes 2.3 * [number_of_digits] attempts to find a prime. The chances are increased greatly by sieving, as you only test preselected numbers. So you can say roughly 0.046 * number_of_digits tasks are required on average.
If you want a mega prime, i.e. one with more than 1 000 000 digits, try PPSmega (CPU) and GFN17mega (GPU). The GFN tasks are very fast on GPUs, so I guess it's the best way to find a mega prime.
All the other subprojects are only interesting if you want to find special types of primes.
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1281979 * 2^485014 + 1 is prime ... no further hits up to: n = 4,400,000  

PDWSend message
Joined: 14 Nov 14 Posts: 19 ID: 373199 Credit: 1,730,336,536 RAC: 63,958

If you want a mega prime, i.e. one with more than 1 000 000 digits
Correction: one with at least 1 000 000 digits
:)  


Cool, thanks so much for all the information. I will become a bit more selective in my projects ;)  


HI Michael, May I offer my own suggestion, as I started here nearly 2 years ago, with little idea of how to proceed, and have become "addicted".
I keep exact records of run times for each sub project I run, for each PC and GPU type. It really shows you where you get good credits, for the input you make.
The higher yielders, as mentioned below will get you started and keep you interested as well. It's great fun to read the messages and see the opinions, you'll learn a lot here from very smart people (not me ;))
Try SGS, PPSE, GFN15, GFN 16. You'll get primes and then you can study the "harder ones too"
Best wishes and good luck.
PS The Tour de Primes from 1st Feb might yield you a prime or two and some good badges.
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Cool and thanks. I think I must also start keeping record of input v. output. That is really a good idea. I never thought it would catch me, but I'm also getting more and more addicted to the numbers :)
I have a fast graphic card, so the "Feeling Lucky" seems to be excellent in terms of scoring credits for a single task.
Thanks again for your help. Very much appreciated.
 

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Help with finding primes 