For interviews and programming puzzles you only need to know notation for basic mathematical logic, basic set theory and the summation notation and maybe some bits and pieces from number theory:

https://en.wikipedia.org/wiki/Logical_connective#Common_logi...

https://en.wikipedia.org/wiki/Quantifier_(logic)#Notation

https://en.wikipedia.org/wiki/Set_theory#Basic_concepts_and_...

https://en.wikipedia.org/wiki/Summation#Capital-sigma_notati...

https://en.wikipedia.org/wiki/Modular_arithmetic#Congruence

If Wikipedia is too hard to follow, you can learn this from early chapters of a discrete mathematics textbook.