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.

Interesting blog about programming, mathematics, Lisp and Plan 9.

Alexandre Stefanov long maintained a list of online math texts and other materials at Geocities, but it appears that his original web site is no longer available. Because these resources may be of interest to our readers, we present here a modified version of Stefanov's list as of November 18, 2009. We welcome corrections or suggested additions to this list.

Interesting blog. I found the article http://bit-player.org/2016/prime-after-prime via Tony Finch's link log http://dotat.at/:

Vincenty's formulae are two related iterative methods used in geodesy to calculate the distance between two points on the surface of a spheroid, developed by Thaddeus Vincenty (1975a) They are based on the assumption that the figure of the Earth is an oblate spheroid, and hence are more accurate than methods such as great-circle distance which assume a spherical Earth.

The first (direct) method computes the location of a point which is a given distance and azimuth (direction) from another point. The second (inverse) method computes the geographical distance and azimuth between two given points. They have been widely used in geodesy because they are accurate to within 0.5 mm (0.020″) on the Earth ellipsoid.

The Mathematics and Computation blog focuses on connections between mathematics and the theory of computation. The blog is owned and written by Andrej Bauer, with occasional guest posts.

Mathematics and computer science notes, includes continued fractions, elliptic curves and a lot more.
See also the link to the home page http://crypto.stanford.edu/~blynn/
where you can find some simple programs in both C and Go, a guide to the git version control system.