English

Recurrence Relations for $\beta(2k)$ and $\zeta(2k + 1)$

General Mathematics 2025-09-03 v2

Abstract

In this work we study integrals of the form 0tanh(x)xsech(x)Lexp(Tx)dx\int_{0}^{\infty}\frac{\tanh(x)}{x}\mathrm{sech}(x)^{L}\exp(-Tx)dx. For LNL \in \mathbb{N}, L4L \leq 4 and TRT \in \mathbb{R} we give explicit expressions in terms of derivatives of the Hurwitz zeta function at negative integers. We use these expressions to evaluate these integrals for TN0T \in \mathbb{N}_{0} exactly. For the special case T=0T = 0 we give explicit evaluations for any LNL \in \mathbb{N} based on the functional equations for β(s)\beta(s) and ζ(s)\zeta(s). As it turns out the value of 0tanh(x)xsech(x)2N+1dx\int_{0}^{\infty}\frac{\tanh(x)}{x}\mathrm{sech}(x)^{2N + 1}dx is a linear combination of β(2)\beta(2), ..., β(2N+2)\beta(2N + 2) and the value of 0tanh(x)xsech(x)2Ndx\int_{0}^{\infty}\frac{\tanh(x)}{x}\mathrm{sech}(x)^{2N}dx a linear combination of ζ(3)\zeta(3), ..., ζ(2N+1)\zeta(2N + 1). We give recursive formulae for the coefficients in these linear combinations.

Keywords

Cite

@article{arxiv.2508.11643,
  title  = {Recurrence Relations for $\beta(2k)$ and $\zeta(2k + 1)$},
  author = {Tobias Kyrion},
  journal= {arXiv preprint arXiv:2508.11643},
  year   = {2025}
}
R2 v1 2026-07-01T04:52:20.134Z