Here are a few notation resources I've found helpful when teaching myself computer science:

- Mathematics for Computer Science: https://courses.csail.mit.edu/6.042/spring17/mcs.pdf

- Calculus Made Easy: http://calculusmadeeasy.org

Not directly related to your question but useful for interviews and programming puzzles nonetheless:

- Algorithms and Data Structures, The Basic Toolbox: https://people.mpi-inf.mpg.de/~mehlhorn/ftp/Mehlhorn-Sanders...

- Basic Proof Techniques: https://www.cse.wustl.edu/~cytron/547Pages/f14/IntroToProofs...