The first part of the lecture introduces to basic combinatorial
sequences like binomial coefficients, partition numbers, or Stirling
numbers.

The main part of the lecture is devoted to the concept of group
actions. This fundamental concept, connecting algebra with
combinatorics, can be viewed as the basis of Polya's counting theory.
Typical applications, for instance, concern different colorings of the
cube, or determining the total number of molecular graphs of a
certain type (e.g., alcohols).