Characterization of the Bernoulli polynomials via the Raabe functional equation

Abstract

The purpose of the present paper is to show that in certain classes of real (or complex) functions, the Bernoulli polynomials are essentially the only ones satisfying the Raabe functional equation. For the class of the real $1$-periodic functions which are expandable as Fourier series, we point out new solutions of the Raabe functional equation, not relating to the Bernoulli polynomials. Furthermore, we will give for the considered classes various proofs, making the mathematical content of the paper quite rich.