I'm looking for maths-related reading but I'm struggling to find something that appeals to me. I have some formal mathematics education, and so properly popular maths writing is usually a bit basic for me, but I also don't want to just sit down and read textbooks.
I want something intended for leisurely reading, but which still requires me to wrap my head around some tricky concepts. Something that scratches the same itch as a 3blue1brown video. Any recommendations appreciated!