Sobre los números de Hal y Lah

In this article we study some properties concerning the Hal (H k n ) and Lah numbers (Lk n ), which are those that arise in the theory of combinatorics in association with the ‘upward and downward factorial polynomials’ [x]n and [x]n. We establish the corresponding recurrence formulas, the generating functions and the closed formulas for this family of numbers, among others properties. Keywords: Hal numbers, Lah numbers, combinatorics, generating functions.