I read "GEB" by Hofstadter after I finished my A levels (UK, aged 18). I picked up a random book in the school library to fill in 20 mins before going out on a pub crawl (as you do). Once we had finished off the Abingdon Ock Street crawl in fine style and the hangover had subsided, I devoured it. I'd never read anything like it before - what a communicator of ideas.

A few unwise life style choices later and I find myself running a small IT company for the last 25 odd years.

I'll never get beyond undergrad engineering maths n stats but it's works like GEB and the Natural Numbers Game (and I see there are more) that allow civilians like me to get a glimpse into the real thing. There is no way on earth I could possibly get to grips with the really serious stuff but then the foundations are the really serious stuff - the rest simply follows on (lol)

Whom or whoever wrote the NNG tutorials are a very good communicator. The concepts are stripped to the bare essentials and the prose is crystal clear and the tone is suitably friendly.

Top stuff.