[seqfan] Re: A002335

Neil Sloane njasloane at gmail.com
Fri Feb 15 18:11:02 CET 2013


I agree, except that the comma should be omitted:
Least y such that A038873(n) = x^2 - 2y^2 for some x.

The comma makes it appear to be
{Least y such that A038873(n) = x^2 - 2y^2}, for some x.
whereas without the comma it is closer to
Least y such that {A038873(n) = x^2 - 2y^2 for some x}.
which is what we want.

On Fri, Feb 15, 2013 at 5:51 AM, Maximilian Hasler <
maximilian.hasler at gmail.com> wrote:

> I propose as new title:
>  Least y such that A038873(n) = x^2 - 2y^2, for some x.
> and change offset to 1.
> Would you kindly re-submit a re-indexed b-file?
>
> Maximilian
>
>
> On Fri, Feb 15, 2013 at 4:26 AM,  <israel at math.ubc.ca> wrote:
> > It seems to me that the title and comment of A002335 do a poor job of
> > explaining what is going on in this sequence. I could only figure it out
> by
> > decyphering the Maple program. If p is the (n-1)'th prime for which a
> > representation p = x^2 - 2 y^2 in positive integers exists, then
> A002335(n)
> > is the least y for such a representation. Note that the representation is
> > generally not unique, e.g. 17 = 5^2 - 2*2^2 = 7^2 - 2*4^2.
> >
> > I also don't know why the offset is 2 here, unless it has something to do
> > with the fact that the first such prime is 2.
> >
> > Robert Israel
> > University of British Columbia
> >
> > _______________________________________________
> >
> > Seqfan Mailing list - http://list.seqfan.eu/
>
> _______________________________________________
>
> Seqfan Mailing list - http://list.seqfan.eu/
>



-- 
Dear Friends, I have now retired from AT&T. New coordinates:

Neil J. A. Sloane, President, OEIS Foundation
11 South Adelaide Avenue, Highland Park, NJ 08904, USA
Phone: 732 828 6098; home page: http://NeilSloane.com
Email: njasloane at gmail.com


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