Want to know how generating functions work?
How about proving the Ramanujan identities? How about doing all that, with *pictures*?

This course I've recently found and this excellent expository video of "The Art of Bijective Combinatorics" is an absolutely stunning way of doing all that!

https://www.viennot.org/abjc.html

https://youtu.be/jQchTFnKBQs?si=f7ws46uLD1egneCi