Not quite the same but I’d never tried project euler before and am having quite a good time. Enjoying it more than any other programming exercises (besides foobar !).
Covers points 1, 3, 4, and has a degree of popularity, which seems mostly internal, especially because accessing discussion threads requires finding the solution, plus probably its age. Because it’s language-agnostic, clojure is working great
It would be fun to see other answers in clojure for anyone who’s never used that site!