The book reviews on https://catonmat.net/top-100-books-part-eight are short, but cover many interesting books.

Nice blog (in appearance, contents and implementation). See https://archive.casouri.cat/note/2018/blog-in-org-mode-revisited/index.html for an update.
An interesting idea for entering mathematical symbols is presented on https://archive.casouri.cat/note/2020/insert-math-symbol-in-emacs/index.html

Neat description of Reed-Solomon error codes and two simple error-correction algorithms, implemented in Python.
Found on https://planet.scheme.org/ via the article
https://jeremykun.com/2020/09/11/searching-for-rh-counterexamples-setting-up-pytest/

I just have browsed, but there are many interesting articles
https://jao.io/blog/2006-03-17-programmers-go-bananas.html category theory
https://jao.io/blog/2020-05-01-dancers-at-the-end-of-time.html sounds like an interesting book.
https://jao.io/blog/2006-07-06-geometrically-speaking.html geometric proofs, Kindergarten Quantum Mechanics
https://jao.io/blog/2020-05-04-observatory.html Mozilla Observatory to check a website's security

Joe Marshall's non-lisp blog. Lisp/Scheme are the subject of his other blog,
Abstract Heresies, Unorthodox opinions on computer science and programming. http://funcall.blogspot.com/

Collection of interesting articles. Found via
https://fermatslibrary.com/s/the-tunnel-of-samos#email-newsletter
from a post on MoHP.

Various number theoretic algrorithms written in the bc(1) programming language.
See also the calculator program http://www.numbertheory.org/calc/krm_calc.htm from the same author.

A reading protocol is a set of strategies that a reader must use in order to benefit fully from reading the text. Poetry calls for a different set of strategies than fiction, and fiction a different set than non-fiction. It would be ridiculous to read fiction and ask oneself what is the author's source for the assertion that the hero is blond and tanned; it would be wrong to read non-fiction and not ask such a question.  This reading protocol extends to a viewing or listening protocol in art and music. Indeed, much of the introductory course material in literature, music and art is spent teaching these protocols.

Mathematics has a reading protocol all its own, and just as we learn to read literature, we should learn to read mathematics.  Students need to learn how to read mathematics, in the same way they learn how to read a novel or a poem, listen to music, or view a painting.  Ed Rothstein’s book, Emblems of Mind, a fascinating book emphasizing the relationship between mathematics and music, touches implicitly on the reading protocols for mathematics.

From the book Rediscovering Mathematics: You Do the Math by Shai Simonson. http://web.stonehill.edu/compsci/RediscoveringMath/RM.html

For a good example, read http://www.evanmiller.org/dont-kill-math.html

13532385396179 = 13 * 53^2 * 3853 * 96179
is a counterexample to a conjecture of John H. Conway.