On the reciprocal sum of lcm of k-tuples

TL;DR

This paper establishes an asymptotic formula for the reciprocal sum of the least common multiple of k-tuples of integers, confirming a conjecture and providing detailed polynomial and error term descriptions.

Contribution

It proves the conjectured asymptotic behavior of the reciprocal sum of lcm of k-tuples, including polynomial degree and error estimates, advancing understanding of number theoretic sums.

Findings

Asymptotic formula for $S_k(x)$ with polynomial main term

Explicit degree of polynomial as $2^k-1$

Error term characterized by $ heta_k$ and epsilon

Abstract

We prove that the reciprocal sum $S_k(x)$ of the least common multiple of $k\geq 3$ positive integers in $\N\cap [1,x]$ satisfies $$ S_k(x)=P_{2^k-1}(\log x)+O(x^{-\theta_k+\epsilon}) $$ where $P$ is a polynomial of degree $2^k-1$ and $\theta_k=\frac{2^k}{(k+1)^{\frac{k+1}2}}\cdot \frac3{2^k+6k-5}$. This was conjectured in Hilberdink, Luca, and T\'{o}th~\cite[Remark 2.4]{HLT}. We also prove asymptotic formulas for similar sums conjectured there.