mersenneforum.org Program for searching all odd-16-digit Aliquot cycles
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2016-05-02, 10:33   #298
Drdmitry

Nov 2011

111010102 Posts

I took over the last range which was not finished: 30000000 - 30500000 and now it is completed!

Now I can say that all odd aliquot cycles with the smallest term of 16 digits are known! Thanks very much to everyone involved. Without your help this project will never be finished.

To be absolutely rigorous, an independent double check is needed. I leave it to enthusiastic ancestors.
Attached Files
 output_odd_10e16_30000001-30500000.txt (937 Bytes, 55 views)

Last fiddled with by Drdmitry on 2016-05-02 at 10:34

 2016-05-02, 15:45 #299 henryzz Just call me Henry     "David" Sep 2007 Cambridge (GMT) 2×5×569 Posts I would suggest thinking about how we can boincify 17 digits and possibly double check 16 digits with it.
 2016-05-03, 08:44 #300 AndrewWalker     Mar 2015 Australia 2×41 Posts Well done! Do you think anything would be achievable for even numbers, such as restricting it to numbers with small factors? Would probably be too hard to do all of them at this stage.
 2016-05-03, 12:56 #301 Drdmitry     Nov 2011 2·32·13 Posts What is next? In principle, there are two natural extensions of the project.To look for all aliquot cycles such that the number, preceding the biggest number in the cycle is even, up to 14 digits long. To look for all aliquot cycles with the minimal element odd and up to 17 digits. The first project will by slightly less time consuming then the current project So it can definitely be accomplished in the reasonable time (less than a year). However it will interfere with EdH search. He mostly looked for cycles of length four, and our potential project will cover cycles of any length, so it still makes sense to perform it. I expect additional 2 - 3 cycles here. The second project will be much longer. I am not sure that it can be accomplished in a reasonable time (at least with the resources used for the current project). Additional problem here is that the amount of sequences which need to be dealt individually will rapidly grow. In the current project we had about 15 of them, but for 17d sequences there will be thousands of them. This is because 17d numbers are quite close to 64 bit numbers capacity, Last fiddled with by Drdmitry on 2016-05-03 at 14:49
 2016-05-03, 14:15 #302 henryzz Just call me Henry     "David" Sep 2007 Cambridge (GMT) 163A16 Posts It should be possible to add something like gmp to the program which would allow extension beyond 64-bits. The even search is going to need exhaustedly extending at some point. How is now different to later? I would hope that we can add resources if we boincify the project.
2016-05-11, 02:17   #303
EdH

"Ed Hall"
Dec 2009

3,253 Posts

Quote:
 Originally Posted by Drdmitry In principle, there are two natural extensions of the project.To look for all aliquot cycles such that the number, preceding the biggest number in the cycle is even, up to 14 digits long. To look for all aliquot cycles with the minimal element odd and up to 17 digits. The first project will by slightly less time consuming then the current project So it can definitely be accomplished in the reasonable time (less than a year). However it will interfere with EdH search. He mostly looked for cycles of length four, and our potential project will cover cycles of any length, so it still makes sense to perform it. I expect additional 2 - 3 cycles here. The second project will be much longer. I am not sure that it can be accomplished in a reasonable time (at least with the resources used for the current project). Additional problem here is that the amount of sequences which need to be dealt individually will rapidly grow. In the current project we had about 15 of them, but for 17d sequences there will be thousands of them. This is because 17d numbers are quite close to 64 bit numbers capacity,
My machines are currently shut down and will be for at least several more weeks. I'm not sure what direction I will take when I start them back up. I might move to some other factoring projects. Please feel free to run that area. I found quite a few 4-cycles and am happy with those, but I also realize that only searching for 4-cycles is very inefficient overall.

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