👉 Catalan numbers are a sequence of integers that occur in various combinatorial problems, such as counting the number of ways to partition an integer into a sum of positive and negative integers. They were first introduced by mathematician Stefan Banach in 1923. The Catalan numbers are named after the Catalan brothers, who were interested in the concept of "cascading" or "catalytic" processes. They are defined as follows: C(n) = (n +