Journal of Integer Sequences, Vol. 27 (2024), Article 24.2.5

On Residues of Rounded Shifted Fractions with a Common Numerator


Nicholas Dent
Department of Mathematics
Boston University Academy
Boston, MA 02215
USA

Caleb M. Shor
Department of Mathematics
Western New England University
Springfield, MA 01119
USA

Abstract:

The proportion of integers

$\displaystyle \lfloor n/1 \rfloor , \lfloor n/2 \rfloor , \dots, \lfloor n/n \rfloor $

that are odd is asymptotically $\log2$. If instead of the floor function, one uses the nearest-integer function, the proportion drops to $\pi/2-1$. In this work, we prove these facts and, more generally, give an integral formula for the proportion of

$\displaystyle \lfloor (n-\nu)/1+\alpha \rfloor ,\, \lfloor (n-\nu)/2+\alpha \rfloor ,\, \dots,\, \lfloor (n-\nu)/n+\alpha \rfloor $

that are congruent to $r$ modulo $m$. We conclude by linking this problem to the Dirichlet divisor and Gauss circle problems, and counting lattice points in other quadratic regions.


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(Concerned with sequences A014202 A038589 A057655 A059851 A330926 A363341.)


Received June 30 2023; revised versions received September 23 2023; January 18 2024. Published in Journal of Integer Sequences, January 20 2024.


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