Enumeration of Up-Down Permutations by Upper Records.
Enumeration of Varlet and Comer hypergroups.
Enumerative problems inspired by Mayer's theory of cluster integrals.
Enumerative properties of generalized associahedra.
Equidistribution and sign-balance on 132-avoiding permutations.
Equidistribution and sign-balance on 321-avoiding permutations.
Equidistribution of descents, adjacent pairs, and place-value pairs on permutations.
Equivalence classes of functions on finite sets.
Erratum: "Embeddings of 2-spheres in 4-manifolds".
Erratum to -primary ideals of a commutative ring
Eulerian calculus. IV: Specializations.
Eulerian numbers and operators.
Euler-Seidel method for certain combinatorial numbers and a new characterization of Fibonacci sequence
In this paper we use the Euler-Seidel method for deriving new identities for hyperharmonic and r-Stirling numbers. The exponential generating function is determined for hyperharmonic numbers, which result is a generalization of Gosper’s identity. A classification of second order recurrence sequences is also given with the help of this method.
Evaluation of divisor functions of matrices
1. Introduction. The study of divisor functions of matrices arose legitimately in the context of arithmetic of matrices, and the question of the number of (possibly weighted) inequivalent factorizations of an integer matrix was asked. However, till now only partial answers were available. Nanda [6] evaluated the case of prime matrices and Narang [7] gave an evaluation for 2×2 matrices. We obtained a recursion in the size of the matrices and the weights of the divisors [1,2] which helped us obtain...
Excedance number for involutions in complex reflection groups.
Excedance numbers for permutations in complex reflection groups.
Exchange symmetries in Motzkin path and bargraph models of copolymer adsorption.
Existence and reduction of generalized Apostol-Bernoulli, Apostol-Euler and Apostol-Genocchi polynomials
One can find in the mathematical literature many recent papers studying the generalized Apostol-Bernoulli, Apostol-Euler and Apostol-Genocchi polynomials, defined by means of generating functions. In this article we clarify the range of parameters in which these definitions are valid and when they provide essentially different families of polynomials. In particular, we show that, up to multiplicative constants, it is enough to take as the “main family” those given by and as an “exceptional family”...
Explicit formulas for Bernoulli and Euler numbers.
Exponential generating function of hyperharmonic numbers indexed by arithmetic progressions
There is a circle of problems concerning the exponential generating function of harmonic numbers. The main results come from Cvijovic, Dattoli, Gosper and Srivastava. In this paper, we extend some of them. Namely, we give the exponential generating function of hyperharmonic numbers indexed by arithmetic progressions; in the sum several combinatorial numbers (like Stirling and Bell numbers) and the hypergeometric function appear.