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ON THE PRIMES IN FLOOR FUNCTION SETS
Published online by Cambridge University Press: 23 November 2022
Abstract
Let $[t]$ be the integral part of the real number t and let
$\mathbb {1}_{{\mathbb P}}$ be the characteristic function of the primes. Denote by
$\pi _{\mathcal {S}}(x)$ the number of primes in the floor function set
$\mathcal {S}(x) := \{[{x}/{n}] : 1\leqslant n\leqslant x\}$ and by
$S_{\mathbb {1}_{{\mathbb P}}}(x)$ the number of primes in the sequence
$\{[{x}/{n}]\}_{n\geqslant 1}$. Improving a result of Heyman [‘Primes in floor function sets’, Integers 22 (2022), Article no. A59], we show
$$ \begin{align*} \pi_{\mathcal{S}}(x) = \int_2^{\sqrt{x}} \frac{d t}{\log t} + \int_2^{\sqrt{x}} \frac{d t}{\log(x/t)} + O(\sqrt{x}\,\mathrm{e}^{-c(\log x)^{3/5}(\log\log x)^{-1/5}}) \quad\mbox{and}\quad S_{\mathbb{1}_{{\mathbb P}}}(x) = C_{\mathbb{1}_{{\mathbb P}}} x + O_{\varepsilon}(x^{9/19+\varepsilon}) \end{align*} $$
for $x\to \infty $, where
$C_{\mathbb {1}_{{\mathbb P}}} := \sum _{p} {1}/{p(p+1)}$,
$c>0$ is a positive constant and
$\varepsilon $ is an arbitrarily small positive number.
MSC classification
- Type
- Research Article
- Information
- Bulletin of the Australian Mathematical Society , Volume 108 , Issue 2 , October 2023 , pp. 236 - 243
- Copyright
- © The Author(s), 2022. Published by Cambridge University Press on behalf of Australian Mathematical Publishing Association Inc.
Footnotes
This work is supported in part by the National Natural Science Foundation of China (Grant Nos. 11971370 and 12071375).
References
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