Vol. 29 (2019)
Articles

A congruence for a double harmonic sum

Tewodros Amdeberhan
Department of Mathematics, Tulane University, New Orleans, LA 70118
Roberto Tauraso
Dipartimento di Matematica, Universita di Roma “Tor Vergata”, 00133 Roma, Italy
Portada

Published 2024-09-04

Keywords

  • harmonic numbers,
  • Euler number,
  • congruences

Abstract

In this short note, our primary purpose is to prove the congruence

\[\sum_{k=1}^{\frac{p-1}{2}} \frac{(-1)^k}{k} \sum_{j=\lfloor\frac{k}{2}\rfloor+1}^{k} \frac{1}{2j-1} \equiv 0 \mod p\]

Along the way, a number of auxiliary results of independent interest are found.