In combinatorics, Stirling numbers arise in a variety of combinatorics problems. They are introduced in the eighteen century by James Stirling. There are two kinds of Stirling numbers: Stirling numbers of the first and second kinds. Every Stirling number of the second kind, usually denoted by S(n,k), is the number of ways of partitioning a set of n elements into k nonempty subsets, may be computed by