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  1. Formula for pentagonal numbers - Mathematics Stack Exchange

    Jul 27, 2013 · Formula for pentagonal numbers Ask Question Asked 12 years, 6 months ago Modified 6 years, 8 months ago

  2. How to prove Euler's pentagonal theorem? Some hints will help

    Aug 5, 2011 · While there is a lot of value to the different bijective proofs known for Euler's pentagonal theorem, perhaps the proof that's easiest to see without having to draw pictures is Euler's original idea.

  3. Is Cairo pentagonal tiling belong to pentagonal tilings type 8?

    Apr 30, 2020 · I agree with you. The type 8 pentagon tiling has one degree of freedom, and although you can choose it so that clusters of four tiles form a large hexagonal shape similar to that seen in …

  4. graph theory - Mathematics Stack Exchange

    A polyhedron has all its faces either pentagons or hexagons. Show that it must have at least $12$ pentagonal faces. I can show that it has exactly $12$ pentagonal faces when exactly $3$ faces meet at

  5. Finding triangular numbers that are also pentagonal

    Finding triangular numbers that are also pentagonal Ask Question Asked 8 years, 11 months ago Modified 8 years, 11 months ago

  6. A New Pentagonal Tiling? Help Me Solve the Mystery

    Feb 10, 2025 · Thank you for your comment! Indeed, all convex pentagonal tilings have been mapped, and the list is believed to be complete. However, for concave pentagons, there are infinitely many …

  7. Pentagonal Numbers - Mathematics Stack Exchange

    Aug 26, 2015 · Pentagonal Numbers Ask Question Asked 10 years, 5 months ago Modified 10 years, 5 months ago

  8. On a pentagonal pyramid, how tall does it need to be so that every ...

    Aug 3, 2025 · But if you raise the center point (turning it into a pentagonal pyramid), it gets closer to having all triangular faces equilateral. How tall does it need to be so that every triangular face is …

  9. algebra precalculus - The $n$-th pentagonal number is the sum of the …

    Mar 13, 2025 · I am a high school student, and while learning about figurate numbers, I came up with a relationship between pentagonal numbers, square numbers, and triangular numbers. I’m wondering …

  10. Why are $10$-sided dice not bipyramids? - Mathematics Stack Exchange

    Jun 12, 2019 · Commonly used $10$ -sided dice are pentagonal trapezohedrons, as opposed to pentagonal bipyramids. Given that bipyramids are a more "obvious" shape for a fair die with an even …