Lah number

The Lah number, denoted as \( L(n, k) \), is a combinatorial number that counts the number of ways to partition \( n \) labeled objects into \( k \) non-empty unlabeled subsets. It can be derived from Stirling numbers of the second kind, denoted \( S(n, k) \), which counts the ways to partition \( n \) labeled objects into \( k \) non-empty labeled subsets.