[pedroth]

"I have long struggled with understanding what probability-generating functions are and how to intuit them. There were two pieces of the puzzle missing for me, and we’ll go through both in this article."

Great article. For more, I really recommend Analytic Combinatorics:

https://ac.cs.princeton.edu/home/

[hintymad]

Second this. This class is a classical example of conceptual blockbuster. Once one learns it, the complexity analysis of algorithms will never be the same again. In general, if a techie wants to spend their spare time learning new stuff, they will be better off focusing more on such conceptual stuff, as the return will compound over the years.