Dear Colleagues, we are pleased to inform you that a Special Issue of the Mathematics Journal (a peer-reviewed open access journal ISSN 2227-7390 https://www.mdpi.com/journal/mathematics <https://www.mdpi.com/journal/mathematics>, WoS impact factor 1.747, Q1 and top 10%) dedicated to polynomial sequences and their applications is now open to receive submission for possible publications. Special Issue: *Polynomial Sequences and Their Applications.* Website:https://www.mdpi.com/journal/mathematics/special_issues/polynomial_sequences... <https://www.mdpi.com/journal/mathematics/special_issues/polynomial_sequences_applications> Guest Editors: Prof. Dr. Francesco Aldo Costabile, Prof. Dr. Maria I. Gualtieri, Prof. Dr. Anna Napoli Department of Mathematics and Computer Science, University of Calabria, Via Pietro Bucci, cubo 30/A, 87036 Rende (CS), Italy. Deadline for manuscript submissions: *30 June 2021.* Potential topics include but are not limited to the following: ·Modern Umbral Calculus (Binomial, Appell, Sheffer Polynomial Sequences). ·Orthogonal polynomials, Matrix orthogonal polynomials, Multiple orthogonal polynomials and Orthogonal polynomials of several variables. ·Operational methods and Monomiality Principle. ·Generating functions, special classes. ·Matrix and determinant approach to special polynomial sequences. ·Applications of special polynomial sequences in approximation theory, in boundary value problems and in quadrature formulas. ·Number theory and special classes of polynomials. ·Asymptotic methods in orthogonal polynomials. ·Fractional Calculus. ·Extrapolation methods. *Description* Polynomials are an incredibly useful mathematical tools as they are simply defined and can be calculated quickly on computer systems. They can be differentiated and integrated easily, and can be pieced together to form spline curves. Furthermore, from Weierstrass’s Approximation Theorem, every continuous function defined on a closed interval can be uniformly approximated by polynomials. Therefore sequences of polynomials perform an important role in several branches of sciences: mathematics, phisics, engineering etc. For examples, polynomial sequences arise in physic and approximation theory as the solutions of certain ordinary differential equations. Orthogonal polynomials play an important role in the applications. In statistics Hermite polynomials are very important, which are, also, orthogonal polynomials. In algebra and combinatorics umbral polynomials are used such as: rising factorials, falling factorials, Abel, Bell, Bernoulli, Euler, Boile, ciclotomic, Dickson, Fibonacci, Lucas, Touchard etc. polynomials. Some of these belong to special classes, such as Sheffer, Appell and the binomial type.For this reason the research in this field appears in different Journals/Magazines. A special issue that makes the state of art of current research would be very useful for the mathematical community. We warmly invite you to contribute to our Special Issue. Don't hesitate to forward this message to anyone who could be interested. Thank you very much for your kind consideration and apologies for multiple copies. We look forward to hearing from you. Francesco A. Costabile, Maria I. Gualtieri, Anna Napoli