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On a series related to the Möbius function
Abstract
For a natural number n>1 let P-(n) denote its smallest prime divisor. Alladi and Johnson proved that ∑P−(n)≡ l Modk μ(n)ω(n)/n = 0 for (l,k)=1, and Tenenbaum showed that the partial sums of this series up to X are Oε((loglog X)5/3+ε/log X). In this article, we prove that these partial sums are in fact equal to C(k,l)/log X + O((loglog X)4/(log X)2), with an explicit constant C(k,l). We also investigate the behaviour of these constants. In particular, we show under GRH that the number of reduced classes lModk for which C(k,l)<0 is $φ(k)(1- o(1))$ as k→∞.
Related
- Explicit formula for the discrete Laplace transform of the Möbius function, related special functions, and a criterion for the Riemann hypothesis
- A Möbius function computing h-polynomials of nestohedra
- Primes and the Möbius function over quadratic polynomials
- Short sums of the Möbius function over function fields
- Chowla Conjecture for the truncated Möbius function over 𝔽q[t]
BibTeX
@misc{thakur2026series,
title = {{On a series related to the Möbius function}},
author = {Deep Thakur},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.23660},
eprint = {2610.23660},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.23660},
}
RIS
TY - UNPB
TI - On a series related to the Möbius function
AU - Deep Thakur
PY - 2026
DA - 2026/10/16
PB - arXiv
DO - 10.48550/arxiv.2610.23660
UR - https://arxiv.org/abs/2610.23660
AB - For a natural number n>1 let P^-(n) denote its smallest prime divisor. Alladi and Johnson proved that ∑_P^−(n)≡ l Modk μ(n)ω(n)/n = 0 for (l,k)=1, and Tenenbaum showed that the partial sums of this series up to X are O_ε((loglog X)^5/3+ε/log X). In this article, we prove that these partial sums are in fact equal to C(k,l)/log X + O((loglog X)^4/(log X)^2), with an explicit constant C(k,l). We also investigate the behaviour of these constants. In particular, we show under GRH that the number of reduced classes lModk for which C(k,l)<0 is $φ(k)(1- o(1))$ as k→∞.
ER -