Journal of Number Theory 128 (2008) 738–758 www.elsevier.com/locate/jnt Degenerate Bernoulli polynomials, generalized factorial sums, and their applications Paul Thomas Young Department of Mathematics, College of Charleston, Charleston, SC 29424, USA Received 14 August 2006; revised 24 January 2007 Available online 7 May 2007 Communicated by David Goss Abstract We prove a general symmetric identity involving the degenerate Bernoulli polynomials and sums of generalized falling factorials, which unifies several known identities for Bernoulli and degenerate Bernoulli numbers and polynomials. We use this identity to describe some combinatorial relations between these poly- nomials and generalized factorial sums. As further applications we derive several identities, recurrences, and congruences involving the Bernoulli numbers, degenerate Bernoulli numbers, generalized factorial sums, Stirling numbers of the first kind, Bernoulli numbers of higher order, and Bernoulli numbers of the second kind. © 2007 Elsevier Inc. All rights reserved. Keywords: Bernoulli numbers; Degenerate Bernoulli numbers; Power sum polynomials; Generalized factorials; Stirling numbers of first kind; Bernoulli numbers of second kind 1. Introduction Carlitz [3,4] defined the degenerate Bernoulli polynomials βm(λ, x) for λ = 0 by means of the generating function ∞ t tm (1 + λt)μx = β (λ, x) (1.1) (1 + λt)μ − 1 m m! m=0 E-mail address:
[email protected]. 0022-314X/$ – see front matter © 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.jnt.2007.02.007 P.T. Young / Journal of Number Theory 128 (2008) 738–758 739 where λμ = 1. These are polynomials in λ and x with rational coefficients; we often write βm(λ) for βm(λ, 0), and refer to the polynomial βm(λ) as a degenerate Bernoulli number.