Two identities involving Cohen-Ramanujan expansions

Fuente: arXiv
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Main Authors: Chandran, Arya, Namboothiri, K Vishnu
Format: Preprint
Published: 2025
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author Chandran, Arya
Namboothiri, K Vishnu
author_facet Chandran, Arya
Namboothiri, K Vishnu
contents An arithmetical function $f$ is said to admit a \emph{Cohen-Ramanujan expansion} $f(n) := \sum\limits_{r}\widehat{f}(r)c_r^s(n)$, if the series on the right hand side converges for suitable complex numbers $\widehat{f}(r)$. Here $c_r^s(n)$ denotes the Cohen-Ramanujan sum defined by E. Cohen. We deduce here a Cohen-Ramanujan expansion for the Jordan totient function $J_k(n)$. Further, we give an an asymptotic formula for the sum $\sum\limits_{n \leq N} \frac{J_a(n)}{n^a} \frac{J_b(n+h)}{(n+h)^b}$ using the expansion we derive.
format Preprint
id arxiv_https___arxiv_org_abs_2503_12027
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Two identities involving Cohen-Ramanujan expansions
Chandran, Arya
Namboothiri, K Vishnu
Number Theory
11A25, 11L03, 11N05, 11N37
An arithmetical function $f$ is said to admit a \emph{Cohen-Ramanujan expansion} $f(n) := \sum\limits_{r}\widehat{f}(r)c_r^s(n)$, if the series on the right hand side converges for suitable complex numbers $\widehat{f}(r)$. Here $c_r^s(n)$ denotes the Cohen-Ramanujan sum defined by E. Cohen. We deduce here a Cohen-Ramanujan expansion for the Jordan totient function $J_k(n)$. Further, we give an an asymptotic formula for the sum $\sum\limits_{n \leq N} \frac{J_a(n)}{n^a} \frac{J_b(n+h)}{(n+h)^b}$ using the expansion we derive.
title Two identities involving Cohen-Ramanujan expansions
topic Number Theory
11A25, 11L03, 11N05, 11N37
url https://arxiv.org/abs/2503.12027