Czechoslovak Mathematical Journal, Vol. 62, No. 4, pp. 1147-1159, 2012

# Generalized Knopp identities for homogeneous Hardy sums and Cochrane-Hardy sums

## Huaning Liu, Jing Gao

Huaning Liu, Department of Mathematics, Northwest University, Xi'an 710069, Shaanxi, P. R. China, e-mail: hnliumath@hotmail.com; Jing Gao, School of Mathematics and Statistics, Xi'an Jiaotong University, Xi'an 710049, Shaanxi, P. R. China, e-mail: jgao@mail.xjtu.edu.cn

Abstract: Let $q$, $h$, $a$, $b$ be integers with $q>0$. The classical and the homogeneous Dedekind sums are defined by
respectively, where
((x))= \begin{cases} x-[x]-\frac12, & \text{if $x$ is not an integer};
0, & \text{if $x$ is an integer}. \end{cases}
The Knopp identities for the classical and the homogeneous Dedekind sum were the following:
\gathered\sum_{d\mid n}\sum_{r=1}^d s\Big(\frac{n}da+rq,dq\Big)=\sigma(n)s(a,q),
\sum_{d\mid n}\sum_{r_1=1}^d\sum_{r_2=1}^d s\Big(\frac{n}da+r_1q,\frac{n}db+r_2q,dq\Big)=n\sigma(n)s(a,b,q),
where $\sigma(n)=\sum\nolimits_{d\mid n}d$. In this paper generalized homogeneous Hardy sums and Cochrane-Hardy sums are defined, and their arithmetic properties are studied. Generalized Knopp identities for homogeneous Hardy sums and Cochrane-Hardy sums are given.

Keywords: Dedekind sum, Cochrane sum, Knopp identity

Classification (MSC 2010): 11F20

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