[seqfan] Re: Purely algorithmic number sequence identification

Neil Sloane njasloane at gmail.com
Tue Feb 24 14:17:28 CET 2015


What do you think of adding your program to Superseeker?  It sounds like
this would definitely be worth doing.

By the way, can you do anything with A122536?  We have 200 terms, but no
formula or recurrence!

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, Feb 23, 2015 at 1:21 PM, Philipp Emanuel Weidmann <
pew at worldwidemann.com> wrote:

> Well, it turns out the first eight elements of A000001 satisfy the, umm,
> "slightly exotic" recurrence relation
>
>   a(1) = 1
>   a(2) = 1
>   a(n) = Floor(a(n-2)*(2-Sin(2^n)))   for n >= 3
>
> ;)
>
> In earnest, while I doubt that brute forcing formulas will bring any
> insight into sequences that have baffled mathematicians for centuries
> with their irregularity, what might indeed be interesting is to run the
> system not on one sequence, but on tens of thousands, all of which have
> no closed-form expression associated with them (is there a way to query
> those on OEIS?). In a matter of days, Sequencer would likely return a
> hundred or so closed forms, some of which may prove correct, which could
> then be investigated rigorously.
>
> For such a search, I should probably also add a lot more combinatorial
> and number theoretic primitives to the formula generator – whenever I
> randomly browse around OEIS, most of the sequences seem to be counting
> problems of some kind.
>
> Best regards
> Philipp
>
>
>
>
> On Mon, 2015-02-23 at 11:02 -0500, W. Edwin Clark wrote:
> > On Mon, Feb 23, 2015 at 5:42 AM, Olivier Gerard <
> olivier.gerard at gmail.com>
> > wrote:
> >
> > >
> > > It would be nice to test it on "hard" sequences and other sequences
> without
> > > formula.
> > >
> > >
> > >
> > For example:  http://oeis.org/A000001, the number of groups of order n
> :-)
> >
> > Or perhaps easier:  http://oeis.org/A000688, the number of abelian
> groups
> > of order n.
> >
> > _______________________________________________
> >
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>
>
>
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