P-1 coordination thread - discussion

[Joh14vers6]

Today I found the factor:
P-1 found a factor in stage #2, B1=130000, B2=2200000.
21181*2^16496492+1 has a factor: 13825033371936547

But I will not get any credit for it because user 13796 (PrimeGrid) already found this factor.
I found that out here: http://www.seventeenorbust.com/sieve/results.txt.bz2
I searched for more tests with already found factors in my worktodo.txt and found another two already found factors by PrimeGrid. So I deleted them from the worktodo.txt.

How can I prevent PrimeGrid finding my factors first?

[shauge]

It is always annoying when not getting credit for a factor found. There is of course no way to prevent sieving finding factors in your factoring range. It is only possible check for found factors before starting factoring. The factor you post is 13.8P which is in a sieve range PrimeGrid did a some time ago and when I look in the "worktodo_16000000_16500000.zip" posted in the "P1 coordination thread", the test you post have been excluded. You should use an updated worktodo file.

[Joe O]

How can I prevent PrimeGrid finding my factors first?

By checking your worktodo.txt against results.txt on a daily basis and removing k n pairs from your worktodo.txt that have already been factored and posted in results.txt.

Edit:

You should use an updated worktodo file.

Thanks shauge. I wrote my answer before seeing your post. I did not consider that Joh14vers6 would have used an obsolete worktoto file. Actually, even my advice to check it daily would not always work. You are correct in saying that there is no way to prevent this from happening.

[shauge]

I can recommend the "make worktodo" site my team mate runesk made to get a worktodo file which eliminates the factors found in the current online results.txt.bz2 file and I will mention my own tool that checks a local worktodo.txt against a locally copied version of results.txt and displays already found factors (take care not to overwrite the prime95 output file "results.txt")