[seqfan] Re: Number of Equilateral Triangles in Regular 3n-gon

[Giovanni Resta]

On 04/08/2013 09:07 AM, Antreas Hatzipolakis wrote:
> Which is the number of the regular triangles bounded by sides and diagonals
> in a regular 3n-gon?

I got
1, 14, 69, 188, 465
as the first 5 terms, but I'm not completely sure
about these values.

I have created a picture of the 69 triangles in the 9-gon,
grouped by size, here : http://www.iread.it/triang.png
just to check we are talking about the same problem.

Giovanni