If a coincidence is really striking and hints at some unknown theory behind it, it's worth publishing as a regular article. [This][1] adroable $1\!\tfrac12$-page paper contains nothing but "numerology"; eventually, it has led to the [monstrous moonshine][2] theory.

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Also, [this question][3] seems relevant.


  [1]: https://doi.org/10.1112/blms/11.3.352
  [2]: https://en.wikipedia.org/wiki/Monstrous_moonshine
  [3]: https://mathoverflow.net/questions/268482/publishing-conjectures