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Old 2020-07-21, 02:45   #7
gd_barnes's Avatar
May 2007
Kansas; USA

241438 Posts

Originally Posted by rogue View Post
Originally the ask was to "remove the check". Now you are asking for software to sieve (k*b^n+c)/d. Although similar, they are not the same. I don't recall anyone asking for this feature before.

For now I have given you a workaround that can be used for d = 2 which is what the original ask was. Why isn't that acceptable? You mention that this forces you to use srsieve for some sequences and srsieve2 for others. Why not srsieve2 for all sequences?

AFAIAC, srsieve is deprecated. sr1sieve and sr2sieve are not. My intention is to add new features to srsieve2, not srsieve. If bugs are found in srsieve then I will certainly fix them, but I'm not inclined to add new features to it.
Where is the workaround that you have stated? I do not see it. I must be dense. lol We do not want to have to input multiple sequences if we only want to sieve one of them. I don't understand.

Please provide a specific example of how we should sieve (13*51^n-1)/2 by sieving 13*51^n-1. Please state the program to use and the command to use. Assume I'm a newbie because I am when it comes to srsieve2.

No we've never asked for srsieve (or srsieve2) to sieve (k*b^n+c)/d. I was just showing an example of what we could sieve with srsieve if the error check for divisibility by 2 is removed. We are just asking for the error check for all candidates divisible by 2 to be removed and then be included in the regular sieving looping process of all other prime factors.

I have used srsieve2 a few times. I find it to be no faster than sr2sieve and find it somewhat more cumbersome to use. I don't care for the fact that the P-rate that it uses is the number of prime factors that it has searched in the last minute whereas the P-rate in srsieve is the P-range that it has searched in the last minute. IMHO the latter is much preferable. I still use srsieve/sr1sieve/sr2sieve for that reason.

Why are you suggesting that we use srsieve2 when you do not know if it will work for what we are asking?

I just tried srsieve2 with the following command:
srsieve2 -p 3 -P 1e6 -n 25e3 -N 100e3 -s "13*51^n-1"

It errored out with:
All terms for sequence 13*51^n-1 are divisible by 2
Fatal Error: All sequences have been removed

So my question is: Why does it error out when I have not included p=2 in the the sieve range ? It should not do that. For the same reason that srsieve should not do that. Sieving 13*51^n-1 by not including the factor of 2 is our way of sieving (13*51^n-1)/2. Does that make sense?

Last fiddled with by gd_barnes on 2020-07-21 at 03:12
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