More Mathematics SE suggestions

[tannerlegvold]

You've already mentioned the triangle of power MSE post, thats a good one. I recently found this which uses over and under bars for $exp$ and $ln$ and juxtaposition for multiplication and writes addition in terms of these. This isn't practical: addition is common enough to need its own symbol, however it is fun and thought provoking. The blog post mentioned in the comments is an ok read as well.

Theres also this which mentions the "correct" way to write the 2nd derivative in Leibniz notation.