I think I'm most interested in works with a clearly mathematical, complex, multi-layered structure or language usage. Like the experiments of Georges Perec [1], for example.

I wonder how would reading this kind of stuff actually stimulate our brain, as compared to solving coding or maths puzzles.

E.g. the book linked above, Perec's "Life: A User's Manual", was "heartly recommended" by Don Knuth [2].

1: https://en.wikipedia.org/wiki/Life:_A_User%27s_Manual

2: https://www-cs-faculty.stanford.edu/~knuth/retd.html