Liked a tweet (Twitter)
This, but also and specifically for mathematics! We need to normalize the idea that math is easy.
Read Tombstone (typography) (Wikipedia)
In mathematics, the tombstone, halmos, end-of-proof, or Q.E.D. symbol "∎" (or "□") is a symbol used to denote the end of a proof, in place of the traditional abbreviation "Q.E.D." for the Latin phrase "quod erat demonstrandum", meaning "which was to be demonstrated". In magazines, it is one of the various symbols used to indicate the end of an article. In Unicode, it is represented as character U+220E ∎ END OF PROOF (HTML ∎). Its graphic form varies, as it may be a hollow or filled rectangle or square.
Replied to a tweet by @fourierfiend (Twitter)
Hello fellow mathematician!

There are lots of ways to syndicate content, some dependent on which platform(s) you’re using and where you’re syndicating to/from. Your best bet is to swing by the IndieWeb Dev chat and ask that very question.

Theorem: Syndication is easy.

Proof: “It’s easy to show” (I’m waving my hands here) that there are a lot of assumptions and baggage that go with the word “easiest.”   ∎

I’ve personally found there’s generally an inverse relationship between ease/simplicity of syndication and control over exact display for most platforms. You could go low-fi and pipe your feed into something like IFTTT/Zapier  for cross-posting all the way up to customized integration with available APIs for each platform. Many take a middle-of-the-road approach that I notice Jeremy recommended as I’m writing this.

The cross-posting wiki page will give you some useful terminology and definitions which may help you decide on how to syndicate what/where. Based on the context of the URL in your Twitter profile, the IndieWeb wiki pages for static site generator and syndication will give you some ideas and options to think about and explore. 

Some of the pages about specific static site generators will give you some code and ideas for how to implement syndication. For example Max Böck has an article Indieweb pt1: Syndicating Content to Twitter, which is Eleventy and Twitter specific, but which could likely be modified for your purposes. SSGs may have some specific peculiarities for syndication that I’m not as familiar with coming from the more dynamic side of the fence.

Since you indicate a language preference for your current site, there’s also a page for Flask with a few users noted there. You might ask Fluffy (usually around in chat) for some advice as I know she syndicates to a few platforms and may have some ideas or even tools/code to share from the Flask perspective.

Q.E.D., right!?

(p.s.: Great Twitter handle!)

Read How a brand of chalk achieved cult status among mathematicians (CNN)
Hagoromo chalk has developed a cult following among mathematicians. When the company went out of business, chaos ensued.
I’ve read this same sort of article in other venues in the past, but closer to the revival of the company. This seems to have cropped up again because the original owner of the Japanese company has passed away in the last month.
Liked a tweet (Twitter)
IndieWeb, cycling, math, AND OER! I’m in… 

How was I not following @geonz before?!

Bookmarked Lecture Notes by Arun DebrayArun Debray (web.ma.utexas.edu)
I LATEXed up lecture notes for many of the classes I have taken; feel free to read through them or use them to review. If you find a mistake or typo, please let me know. If you want to look over the .tex source for any of these notes, please send me an email.
A great set of LaTeXed notes from a variety of coursework.

via Rama Kunapuli.

Read - Want to Read: An Invitation to Applied Category Theory by Brendan Fong (Cambridge University Press)
Category theory is unmatched in its ability to organize and layer abstractions and to find commonalities between structures of all sorts. No longer the exclusive preserve of pure mathematicians, it is now proving itself to be a powerful tool in science, informatics, and industry. By facilitating communication between communities and building rigorous bridges between disparate worlds, applied category theory has the potential to be a major organizing force. This book offers a self-contained tour of applied category theory. Each chapter follows a single thread motivated by a real-world application and discussed with category-theoretic tools. We see data migration as an adjoint functor, electrical circuits in terms of monoidal categories and operads, and collaborative design via enriched profunctors. All the relevant category theory, from simple to sophisticated, is introduced in an accessible way with many examples and exercises, making this an ideal guide even for those without experience of university-level mathematics.
earlier draft available on arXiv