[seqfan] Re: Anyone have a 3-D "Ulam" spiral?

Rémy Etc remyetc9 at gmail.com
Thu Apr 29 07:08:01 CEST 2021


> > Maybe similar thing expressed a different way?:  On a cube make a
> > horizontal spiral outwards on the top face, horizontal loops around to
> > traverse the sides, and a horizontal spiral inwards on the bottom face.
> > Then next layer by step down and spiral outwards on the bottom face, etc.
> >
> > I think this needs at least 1 diagonal step in the loops so as to make
> > the spiral-inwards begin at a corner.  A diagonal step is unlike the 2D
> > spiral of course.  Could have every loop-around take a diagonal step at
> > its end so each loop begins on a corner.

to avoid a diagonal step :
- start with two adjacent points instead of one,
- and then process the points on the successive enclosing square cuboids,
- this idea is depicted here: https://ibb.co/8b3Ttwd

best regards,


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