Various problems lead to the same class of functions from integers to integers: functions having integral difference ratio, i.e. verifying \(f(a)-f(b)\equiv 0 \pmod { (a-b)}\) for all \(a>b\). In this paper we characterize this class of functions from \({\mathbb Z}\) to \({\mathbb Z}\) via their à la Newton series expansions on a suitably chosen basis of polynomials (with rational coefficients). We also exhibit an example of such a function which is not polynomial but Bessel like.
Keywords
- Number Theory
- Theoretical Computer Science