Because some of the problems require a lot formulas and equations to explain what is going on, I've included a documentation feature that converts source files into LaTeX documents.
Now that I'm using Emacs as my main editor I'm writing all of my notes in org-mode, which has good support for literate programming and inline-LaTeX.
With org-babel and a few lines of glue code, I can now write & execute Euler Lisp code blocks directly in my org documents.
For example, to find the sum of all numbers from 1 to 2000 that are multiples of either 2 or 7:
(sum-if 1 2000 &(or (divides? 2 &1) (divides? 7 &1)))
Or to find the largest prime factor of 12345:
(ffst (prime-factors 12345))