20090926, 08:31  #1 
(loop (#_fork))
Feb 2006
Cambridge, England
2×7×461 Posts 
YA aliquotsequencechasing script
Here's the python script I've been using to chase aliquot sequences.
The input file is <number> <index in sequence> then a long list of primes that turned out to be useful (order doesn't matter); just run python aliquot.py <input filename>, and it will add new useful primes to the bottom. Features: incremental ECM, selftiming GNFS with recovery from not having enough relations, reasonably optimised crossover GNFS/MPQS and between different GNFS sizes, nice and small and written in fairly clear Python. Can be stopped at any point in ECM or GNFS and will restart at the same place; I haven't bothered tracking where the temporary directory for msieve is so it doesn't restart msieve MPQS jobs, but it should never run one of those for more than about half an hour. Set the PROG_ variables at the top to something appropriate; you need ecm, msieve and a directory with gnfslasieve4I11e through gnfslasieve4I13e in it. Last fiddled with by fivemack on 20090926 at 08:33 
20090926, 09:30  #2 
Oct 2004
Austria
2·17·73 Posts 
11e vs. 12e?
For which ranges of input size (GNFS resp. SNFS) do you use 11e; where is the approx. crossover between 11e and 12e?
Last fiddled with by Andi47 on 20090926 at 09:31 
20090926, 09:40  #3 
(loop (#_fork))
Feb 2006
Cambridge, England
6454_{10} Posts 
This is a pureGNFS script; I found that 11e was better than MPQSwithmsieve or than 12e from about 85 to about 93 digits. Though I may be confounding things by using 23bit large primes with 11e and 24bit with 12e. Just not enough data points to be certain.

20090926, 10:24  #4  
Jun 2003
2^{2}·7·193 Posts 
Quote:


20090928, 16:30  #5 
May 2009
Dedham Massachusetts USA
3·281 Posts 
I am not understanding exactly what this does. Are you giving a list of primes you want to run ggnfs and ecm on? what does the aliqueit part do? Or are the primes, the known primes of that index of the given seq?

20090928, 16:40  #6 
(loop (#_fork))
Feb 2006
Cambridge, England
2·7·461 Posts 
You give it the starting point, and you give it a list of primes which divide some numbers in the sequence after that starting point; it refactorises everything, it's just that the first method it uses is trial division by a set of primes known to include the factors, which is really quick.
And then having done the factorisation it computes sigma(n)n and continues. 
Thread Tools  
Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Aliquot sequence reservations  schickel  Aliquot Sequences  3707  20220926 16:05 
Useful aliquotsequence links  10metreh  Aliquot Sequences  4  20211028 22:17 
Script for Recognised Generalised Fermat sequence A^2+1  pepi37  Linux  0  20160229 11:57 
Another Aliquot Sequence site  schickel  Aliquot Sequences  67  20120120 17:53 
Aliquot sequence convergence question  philmoore  Math  3  20090320 19:04 