[seqfan] Re: Wanted: suggestions of new sequences for poster
susanne.wienand at gmail.com
Tue Nov 27 07:03:15 CET 2012
To my opinion, meanders also look nice. An example is in the attachment.
That one is counted by A197654.
2012/11/25 Georgi Guninski <guninski at guninski.com>
> Got some knew ones, including colored circles.
> Define x,y=inverse_cantor_pairing(n) - this appears related to:
> A048147 Array T read by diagonals; T(i,j) = i^2 + j^2.
> a(n)=x^2+y^2 mod 2^11 gives circles both in grayscale and
> colormap prism_r.
> a(n)=x^4+y^4 mod n gives something remotely resembling fractals.
> Uploaded the new images.
> The color circles are:
> x^2+y^2 mod 2^11 colormap prism_r maybe A048147 mod 2^11.png
> Most of them look better when looked at smaller ratio.
> On Sun, Nov 25, 2012 at 10:31:50AM +0200, Georgi Guninski wrote:
> > Here is an idea for plotting sequences in 2d.
> > Chose a bijection f: N^2 -> N (I experimented with Cantor pairing).
> > Set the "value" of (x,y) to a( f(x,y) ).
> > Interpret the "value" as color. If working with grayscale,
> > smaller is darker. You can map to RGB or HSV.
> > Probably sequences with small range are better.
> > I experimented with a(n): n mod 2, n mod 5, is_prime(n), sigma_0(n)
> > and in sigma_0(n) got diagonal structure that if true is strange to me.
> > Here are some examples in sage (can't set legend yet so read the
> > name).
> > http://stefan.guninski.com/oeisposter/
> > Note that the png images might contain compression artifacts
> > and I might well have screwed the coding/logic...
> > For other ideas check this mathoverflow post (discussing compression
> > visual artifacts):
> > On Sat, Nov 24, 2012 at 06:57:44PM -0500, Neil Sloane wrote:
> > > Dear Seq Fans, 3 years ago David Applegate and I made
> > > a poster to celebrate the birth of the OEIS Foundation.
> > > It contains 25 of my favorite sequences (you can download it
> > > from the OEIS Foundation web site, http://oeisf.org).
> > >
> > > I would like to make a new poster, to give out at the big
> > > AMS meeting in San Diego in January. Can people send me
> > > suggestions of sequences that have been added to
> > > the OEIS in the past couple of years that would
> > > be good material for the poster? Naturally sequences that
> > > have a striking image associated with them are especially welcome.
> > >
> > > Neil
> > >
> > > _______________________________________________
> > >
> > > Seqfan Mailing list - http://list.seqfan.eu/
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