need guidance on Exact Cover of a Hexagon side (N) with 6 instances of n^2 connected equilateral triangles

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thomas Young

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Oct 3, 2026, 12:12:40 AM (8 days ago) Oct 3
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Hello seqfans!

This may not be new:

I ask for help in verifying this claim for an OEIS sequence:  The number of ways a regular hexagon of side length n, composed of 6n2 equilateral triangles, can be tiled with 6 instances of a connected figure of n2 equilateral triangles is the sequence:  1, 3, 16, 216, . Mirror images are not double ocunted..


See more information and pictures at:


Link


with highest regards.


Tom Young

 


Rémy Etc

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Oct 3, 2026, 1:31:00 AM (8 days ago) Oct 3
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Thomas, I really like the construction you're proposing, and find the illustrations superb.
the solutions have rotational symmetry, only of order 3 or 6 if I'm not mistaken; it might be interesting to count the solutions for a given order.
best regards,
Rémy

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L. Edson Jeffery

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Oct 3, 2026, 9:43:29 AM (8 days ago) Oct 3
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Nice. For n large enough, if you relax the condition that all of the tiles be congruent, then more tilings are possible by combining tiles that fit together to exactly fill a rhombus with side lengths n in more than one way.

Ed Jeffery 
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