Carl Størmer and his Numbers

Fuente: arXiv
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Auteurs principaux: Kroesche, Matthew, Littlejohn, Lance L., Reinhart, Graeme
Format: Preprint
Publié: 2025
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author Kroesche, Matthew
Littlejohn, Lance L.
Reinhart, Graeme
author_facet Kroesche, Matthew
Littlejohn, Lance L.
Reinhart, Graeme
contents In many proofs of Fermat's Two Squares Theorem, the smallest least residue solution $x_0$ of the quadratic congruence $x^2 \equiv -1 \bmod p$ plays an essential role; here $p$ is prime and $p \equiv 1 \bmod 4$. Such an $x_0$ is called a Størmer number, named after the Norwegian mathematician and astronomer Carl Størmer (1874-1957). In this paper, we establish necessary and sufficient conditions for $x_0 \in \mathbb{N}$ to be a Størmer number of some prime $p \equiv 1 \bmod 4$. Størmer's main interest in his investigations of Størmer numbers stemmed from his study of identities expressing $π$ as finite linear combinations of certain values of the Gregory-MacLaurin series for $\arctan(1/x)$. Since less than 600 digits of $π$ were known by 1900, approximating $π$ was an important topic. One such identity, discovered by Størmer in 1896, was used by Yasumasa Kanada and his team in 2002 to obtain 1.24 trillion digits of $π$. We also discuss Størmer's work on connecting these numbers to Gregory numbers and approximations of $π$.
format Preprint
id arxiv_https___arxiv_org_abs_2511_03030
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Carl Størmer and his Numbers
Kroesche, Matthew
Littlejohn, Lance L.
Reinhart, Graeme
History and Overview
Number Theory
In many proofs of Fermat's Two Squares Theorem, the smallest least residue solution $x_0$ of the quadratic congruence $x^2 \equiv -1 \bmod p$ plays an essential role; here $p$ is prime and $p \equiv 1 \bmod 4$. Such an $x_0$ is called a Størmer number, named after the Norwegian mathematician and astronomer Carl Størmer (1874-1957). In this paper, we establish necessary and sufficient conditions for $x_0 \in \mathbb{N}$ to be a Størmer number of some prime $p \equiv 1 \bmod 4$. Størmer's main interest in his investigations of Størmer numbers stemmed from his study of identities expressing $π$ as finite linear combinations of certain values of the Gregory-MacLaurin series for $\arctan(1/x)$. Since less than 600 digits of $π$ were known by 1900, approximating $π$ was an important topic. One such identity, discovered by Størmer in 1896, was used by Yasumasa Kanada and his team in 2002 to obtain 1.24 trillion digits of $π$. We also discuss Størmer's work on connecting these numbers to Gregory numbers and approximations of $π$.
title Carl Størmer and his Numbers
topic History and Overview
Number Theory
url https://arxiv.org/abs/2511.03030