Asymptotics of the Eulerian numbers revisited: A large deviation analysis

Guy Louchard1
1UNIVERSITÉ LIBRE DE BRUXELLES, BELGIUM, DÉPARTEMENT D’INFORMATIQUE, CP 212, BOULEVARD DU TRIOMPHE, B-1050 BRUXELLES, BELGIUM

Abstract

Using the Saddle point method and multiseries expansions, we obtain from the generating function of the Eulerian numbers \( A_{n,k} \) and Cauchy’s integral formula, asymptotic results in non-central region. In the region \( k = n – n^\alpha \), \( 1 > \alpha > 1/2 \), we analyze the dependence of \( A_{n,k} \) on \(\alpha\). This paper fits within the framework of Analytic Combinatorics.

Keywords: Eulerian numbers, Asymptotics, Saddle point method, Multiseries expansions, Analytic Combinatorics.