I've been thinking about the fact that an n×n square grid has as many cells as a triangular lattice with n triangles on each side.
Is there a nice continuous bijection between them? When n is odd, you can at least keep one line of symmetry throughout.

If you're going to be pedantic about the new decade starting in 2021 because "there was no year 0", then you also have to be pedantic about the new decade starting on January 11, 2021, because there were no October 5-14, 1582. :steven_pun:

This is the (co)end, my only (co)friend
Article by Loregian, Fosco
In collection: Attention-grabbing titles
The present note is a recollection of the most striking and useful applications of co/end calculus. We put a considerable effort in making arguments and constructions rather explicit: after having given a series of preliminary definitions, we...
URL: arxiv.org/abs/1501.02503
PDF: arxiv.org/pdf/1501.02503v2
Entry: read.somethingorotherwhatever.

Puzzle of the day: find a number that is a perfect square with exactly 300 times the digit 1 and where all other digits are 0.

I'll answer to the toot and give a solution there.

me doing math and not worrying about when it's due: haha love to learn about these funky little numbers
me when i remember the deadlines: ah fuck the numbers contain depression

To ask is a temporary shame, not to ask a life-long shame -- Japanese proverb

time to crack on with some more EGA proofreading :qed:


A Mastodon instance for maths people. The kind of people who make \(\pi z^2 \times a\) jokes. Use \( and \) for inline LaTeX, and \[ and \] for display mode.