[seqfan] Re: Extending the superseeker

[Robert Gerbicz]

2010/8/20 Georgi Guninski <guninski at guninski.com>

> very nice and fast program thanks!
>
> looks like this will be a useful feature to add (especially if the examined
> sequence |s| doesn't start with the right offset):
>
> s[n]=s1[n+k1]+s2[n+k2]
> where k1,k2 are small, possibly negative (may need to drop first terms of
> |s|).
>
> btw, does seeker.c have a license?
>
>
> On Sat, Aug 14, 2010 at 01:05:54AM +0200, Robert Gerbicz wrote:
> > Currently the superseeker is unable to find identities such that for a
> given
> > s sequence:
> > s1+s2=s
> > s1-s2=s
> > s1*s2=s
> > s1/s2=s
> > where s1 and s2 are existing A sequences. But we can do it very quickly,
> > just sort the A sequences in lexicographic order and do binary search if
> you
> > fix s2. The only weak point is that finding s1*s2=s is only possible (in
> > this fast way) if s1 (or s2) has got only non-zero terms (this is true
> for
> > example if s has got no zero terms), because the solution of a*x=b is not
> > unique if a=b=0.
> >
> > Note that the code prints the solutions only if both s1 and s2 has got no
> > less terms than s.
> >
> > See my seeker.c that finds all these type of identities. You need gmp
> > program (and currently about 210 MB of Ram). The program needs the
> stripped
> > file from the main page (download stripped.gz and extract it).
> >
> > Just an example for 4 sequences:
> >
> > Read sequences from stripped file.
> > Number of sequences=178308
> > Sort is done.
> > Give the integer sequence, terms seperated by commas or spaces (one
> sequence
> > per line)
> > 4 7 10 19 35 83 210 591 1699 5021 14905 44556 133254 399340
> > // Read sequence has got 14 terms.
> > =A001998+A072716
> > Number of found identities=1, time=1 sec.
> >
> > -4 -55 -90 -124 -171 -193 -204 -226 -279 -313 -366 -400 -429
> > // Read sequence has got 13 terms.
> > =A045506-A051227
> > Number of found identities=1, time=1 sec.
> >
> > 1 4 12 98 627 7800 80769 1337670 16365165 306808450 4093063920
> > // Read sequence has got 11 terms.
> > =A006384*A007481
> > Number of found identities=1, time=1 sec.
> >
> > 4 0 3 5 12 24 45 180 455 928 1809 9510
> > // Read sequence has got 12 terms.
> > =A005589*A005043
> > =A052360*A005043
> > Number of found identities=2, time=1 sec.
>
> >
> > _______________________________________________
> >
> > Seqfan Mailing list - http://list.seqfan.eu/
>
>
>
> _______________________________________________
>
> Seqfan Mailing list - http://list.seqfan.eu/
>

You can use/reuse/modify my code.