This is super interesting. I love how concisely they are able to convey a certain concept. I feel the ratio: amount of knowledge you acquire versus length of the explanation is incredibly high, which makes me want to keep opening more and more tabs. The only place where I have the same feeling is in fermatslibrary.com, although in a different way. I would like to see the same concept applied to CS.
For more random interesting theorems with outrageously clever and beautiful proofs, the "Proofs from THE BOOK" [1] book is a fantastic collection. As a curiosity, "THE BOOK" in the title comes from Erdos, who often referred to the book in which God keeps nice proofs of math theorems :)<p>[1]: <a href="https://www.amazon.com/Proofs-BOOK-Martin-Aigner/dp/3642008550" rel="nofollow">https://www.amazon.com/Proofs-BOOK-Martin-Aigner/dp/36420085...</a>
Am I the only one who was confused what the 'tau' referred to in <a href="http://www.theoremoftheday.org/NumberTheory/Willans/TotDWillans.pdf" rel="nofollow">http://www.theoremoftheday.org/NumberTheory/Willans/TotDWill...</a> ?
This is really interesting, but my heart hurts at the SEO value lost in having the main content be all PDFs. Not that there's really a NEED to have all of this crawl-able & indexable by search engines, but it could probably reach a whole lot more people if it was.
I disagree with the front page of this site, the "crowning achievements of mathematics" are not "her theorems", but our definitions.