[seqfan] Re: Mystery concerning sequences A169720-A169727

D. S. McNeil dsm054 at gmail.com
Mon Dec 3 04:39:36 CET 2012


> I don't get the part where you count "3 triangles containing the
> central hexagon", and "3 large triangles containing the white
> hexagon". In each case I only see two triangles in the image at
> oeis.org/A169720/a169720b.jpg  If you're counting a triangle twice,
> why not count both of them twice?

I simply worked backward from what it looked like I needed to count in
order for the total to be right.  There are three points on one side
of the vertical axis which can serve as the peak of a triangle, I
needed the number three, so I decided that was how they were to be
counted.  I could be as easily convinced it's really 2 such triangles
+ 1 of something else.

BTW, those are some gorgeous pictures on your page!


Doug


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