Reciprocity formulas for certain generalized Hardy-Berndt sums
Yuan He
TL;DR
This work extends Hardy–Berndt reciprocity to a broad class of generalized sums $S_{m,n}^{(5)}$ built from the quasi-periodic Euler functions $\overline{E}_m$ and Bernoulli functions $\overline{B}_n$ by employing Fourier-series methods and the periodic zeta/Lerch zeta frameworks. The authors derive new reciprocity formulas, including non-coprime and multi-parameter extensions, which subsume Hardy’s original reciprocity as a special case. The results are presented via two main theorems, with detailed auxiliary lemmas enabling explicit evaluations of Fourier coefficients and sums over diophantine solutions. Collectively, the paper broadens the landscape of reciprocity relations for generalized Hardy-Berndt sums and connects them to classical zeta-function techniques, offering new identities and corollaries such as refined forms of $s_{5}(a,b)$ in terms of GCDs and Euler/Bernoulli constructs.
Abstract
In this paper, we establish some reciprocity formulas for certain generalized Hardy-Berndt sums by using the Fourier series technique and some properties of the periodic zeta function and the Lerch zeta function. It turns out that one of Hardy's reciprocity theorems is deduced as a special case.
