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Bibliographic Details
Main Authors: Armbruster, Ashley, Barger, Grace, Bykova, Sofya, Dvorachek, Tyler, Eckard, Emily, Harrington, Joshua, Sun, Yewen, Wong, Tony W. H.
Format: Preprint
Published: 2020
Subjects:
Online Access:https://arxiv.org/abs/2010.08085
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Table of Contents:
  • In this paper, we investigate the existence of Sierpiński numbers and Riesel numbers as binomial coefficients. We show that for any odd positive integer $r$, there exist infinitely many Sierpiński numbers and Riesel numbers of the form $\binom{k}{r}$. Let $S(x)$ be the number of positive integers $r$ satisfying $1\leq r\leq x$ for which $\binom{k}{r}$ is a Sierpiński number for infinitely many $k$. We further show that the value $S(x)/x$ gets arbitrarily close to 1 as $x$ tends to infinity. Generalizations to base $a$-Sierpiński numbers and base $a$-Riesel numbers are also considered. In particular, we prove that there exist infinitely many positive integers $r$ such that $\binom{k}{r}$ is simultaneously a base $a$-Sierpiński and base $a$-Riesel number for infinitely many $k$.