[seqfan] Re: Update on Java implementations of OEIS sequences

Sean A. Irvine sairvin at gmail.com
Mon Dec 21 23:01:24 CET 2020


Try:

https://github.com/archmageirvine/joeis/blob/master/src/irvine/oeis/a000/A000001.java

In general, for Axxxyyy:

https://github.com/archmageirvine/joeis/blob/master/src/irvine/oeis/axxx/Axxxyyy.java

Unfortunately for A000001 that by itself will not be particularly
illuminating.  Under the hood this one is actually the same kind of cheat
that I was complaining about -- it just consults a precomputed table of
small groups.  I actually previously had an implementation based on known
rules (like those by Mitch Harris in the OEIS entry, in turn based on J. H.
Conway, Heiko Dietrich and E. A. O'Brien), but those rules do not allow one
to go very far.

In general we do not link the Java programs into the OEIS entries -- that
would be 100k edits!.  I tend to only do so if there is not already a
program in some other language, it is non-trivial, or if the implementation
is informative in some way.

Sean.


On Tue, 22 Dec 2020 at 10:49, Neil Sloane <njasloane at gmail.com> wrote:

> Sean, Georg - 100000 programs, that's amazing!
>
> How does one find the program for a sequence?  I was curious to see what
> you do for the core sequence A000001, the number of groups of order n.  I
> went to https://github.com/archmageirvine/joeis, but I did not see how to
> search for A000001.  Obviously I'm not a regular github user.
>
> And I didn't see any mention of Java in https://oeis.org/A000001
>
> Best regards
> Neil
>
> Neil J. A. Sloane, President, OEIS Foundation.
> 11 South Adelaide Avenue, Highland Park, NJ 08904, USA.
> Also Visiting Scientist, Math. Dept., Rutgers University, Piscataway, NJ.
> Phone: 732 828 6098; home page: http://NeilSloane.com
> Email: njasloane at gmail.com
>
>
>
> On Mon, Dec 21, 2020 at 3:56 PM Sean A. Irvine <sairvin at gmail.com> wrote:
>
> > We are pleased to report that the jOEIS now covers over 100000 (29%) of
> > sequences from the database including over 95% of sequences below A037000
> > and all but 5 of the "core" sequences.  We did not keep track, but there
> > have been many corrections and extensions in the OEIS as a result of this
> > effort.
> >
> > We would both like to thank all the members of the seqfan community that
> > answered our various questions, provided example code, or helped with the
> > review of the corresponding OEIS entry changes this year.  In particular,
> > Joerg Arndt, Brian Galebach, Volker Gebhardt, Alois Heinz, Mong Lung
> Lang,
> > Peter Luschny, Simon Plouffe, Seiichi Manyama, Michel Marcus, Richard
> > Mathar, Neil Sloane, and Michael Somos.
> >
> > These are the remaining "core" sequences for which we do not have an
> > implementation:
> >
> > A000019 Number of primitive permutation groups of degree n.
> > A000112 Number of partially ordered sets ("posets") with n unlabeled
> > elements.
> > A000609 Number of threshold functions of n or fewer variables.
> > A001034 Orders of non-cyclic simple groups (without repetition).
> > A002106 Number of transitive permutation groups of degree n.
> >
> > It would be nice to have programs (real programs -- not a cheat like the
> > table lookup in A000019) for each of these in any language!
> >
> > Perhaps some of these would make good honors projects or part of a
> masters
> > project.
> >
> > For more information about the jOEIS project, see
> > https://github.com/archmageirvine/joeis
> >
> > Regards,
> > Sean A. Irvine and Georg Fischer
> >
> > --
> > Seqfan Mailing list - http://list.seqfan.eu/
> >
>
> --
> Seqfan Mailing list - http://list.seqfan.eu/
>



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