[seqfan] Re: A132870 : a Mathematica line

[Neil Sloane]

Since the triangle is integral for a long time, I think it is enough to
leave the entry the way it is, but to make it clear in the comments that
this stops being integral beyond a certain point.

There is a famous recurrence (discussed by Lenstra) which is integral for
48 or so terms but then isn;'t, and we handled that in the same way.  We
pretend it is integral, but add a warning that it really isn't.
And we stop the b-file before we hit the rocks.


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, Nov 20, 2017 at 12:47 PM, Paul Hanna <pauldhanna.math at gmail.com>
wrote:

> Wouter,
>       Thanks for verifying the fractional elements.
> "Bummer" is right ...
> I'll ask Neil what to do with the non-integral triangle.
> Thank you!
>       Paul
>
> On Sat, Nov 18, 2017 at 11:50 AM, Wouter Meeussen <
> wouter.meeussen at telenet.be> wrote:
>
> > pt = {{1}}; Table[rhs = CoefficientList[(k^2 + x)^k, x];
> > qt = Join[pt, {vars = Array[Subscript[a, #] &, k + 1]}];
> > b = MatrixPower[PadRight[qt], k] ;
> > {out} = vars /. Solve[Thread[Reverse[Last[b]] == Reverse[rhs]], vars];
> > pt = Join[pt, {out}]; out, {k, 20}]
> >
> >
> > not the fastest of codes : the first 20 rows take 43 seconds on my old
> > machine.
> >
> >
> > W.
> >
> > --
> > Seqfan Mailing list - http://list.seqfan.eu/
> >
>
> --
> Seqfan Mailing list - http://list.seqfan.eu/
>