Those problems, while heavily math-oriented, sure look like a lot of fun. I’d recommend them for students, especially, as well as anyone starting out who doesn’t have a solid base of code samples to show to prospective employers.
Many of those problems, I assume, have been around for decades. I remember, back when I started programming (in the 80s!), we did some challenges like some of those (e.g., find the 1000th prime, etc.). Back then, some of those problems meant hitting go & coming back to the machine the next day. It reminds me now that advanced mathematics can, and does, come in handy for many of those. My friends and I thought we were pretty clever finding the Xth prime in just a day or so… Then our one friend’s dad, an engineer, patched out code w/some advanced stuff that none of us understood, and he had the answer is considerably less time. (I can’t recall if it was like hours or minutes, but it put us highschool algebra-types to shame.)
These days, I do *web* development. Quite a lot of that is not math-oriented code. But, understanding programming logic (which those problems will teach) certainly comes into play daily. Wish I had some client to pay me to do all of those problems, of course… ;-)