Characterization of Chebyshev Numbers

Let Tn(x) be the degree-n Chebyshev polynomial of the first kind. It is known [1,13] that Tp(x)≡xpmodp, when p is an odd prime, and therefore, Tp(a)≡amodp for all a. Our main result is the characterization of composite numbers n satisfying the condition Tn(a)≡amodn, for any integer a. We call these...

Full description

Saved in:
Bibliographic Details
Published in:Algebra and Discrete Mathematics
Date:2008
Main Authors: Jacobs, D.P., Trevisan, V., Rayers, M.O.
Format: Article
Language:English
Published: Інститут прикладної математики і механіки НАН України 2008
Online Access:https://nasplib.isofts.kiev.ua/handle/123456789/152391
Tags: Add Tag
No Tags, Be the first to tag this record!
Journal Title:Digital Library of Periodicals of National Academy of Sciences of Ukraine
Cite this:Characterization of Chebyshev Numbers / D.P. Jacobs, V. Trevisan, M.O. Rayers // Algebra and Discrete Mathematics. — 2008. — Vol. 7, № 2. — С. 65–82. — Бібліогр.: 17 назв. — англ.

Institution

Digital Library of Periodicals of National Academy of Sciences of Ukraine
id nasplib_isofts_kiev_ua-123456789-152391
record_format dspace
spelling Jacobs, D.P.
Trevisan, V.
Rayers, M.O.
2019-06-10T19:03:32Z
2019-06-10T19:03:32Z
2008
Characterization of Chebyshev Numbers / D.P. Jacobs, V. Trevisan, M.O. Rayers // Algebra and Discrete Mathematics. — 2008. — Vol. 7, № 2. — С. 65–82. — Бібліогр.: 17 назв. — англ.
1726-3255
2000 Mathematics Subject Classification:11A07, 11Y35.
https://nasplib.isofts.kiev.ua/handle/123456789/152391
Let Tn(x) be the degree-n Chebyshev polynomial of the first kind. It is known [1,13] that Tp(x)≡xpmodp, when p is an odd prime, and therefore, Tp(a)≡amodp for all a. Our main result is the characterization of composite numbers n satisfying the condition Tn(a)≡amodn, for any integer a. We call these pseudoprimes Chebyshev numbers, and show that n is a Chebyshev number if and only if n is odd, squarefree, and for each of its prime divisors p, n≡±1modp−1 and n≡±1modp+1. Like Carmichael numbers, they must be the product of at least three primes. Our computations show there is one Chebyshev number less than 10¹⁰, although it is reasonable to expect there are infinitely many. Our proofs are based on factorization and resultant properties of Chebyshev polynomials.
Research partially supported by CNPq - Grants 478290/04-7 and 43991/2005-0;and FAPERGS - Grant 05/2024.1
en
Інститут прикладної математики і механіки НАН України
Algebra and Discrete Mathematics
Characterization of Chebyshev Numbers
Article
published earlier
institution Digital Library of Periodicals of National Academy of Sciences of Ukraine
collection DSpace DC
title Characterization of Chebyshev Numbers
spellingShingle Characterization of Chebyshev Numbers
Jacobs, D.P.
Trevisan, V.
Rayers, M.O.
title_short Characterization of Chebyshev Numbers
title_full Characterization of Chebyshev Numbers
title_fullStr Characterization of Chebyshev Numbers
title_full_unstemmed Characterization of Chebyshev Numbers
title_sort characterization of chebyshev numbers
author Jacobs, D.P.
Trevisan, V.
Rayers, M.O.
author_facet Jacobs, D.P.
Trevisan, V.
Rayers, M.O.
publishDate 2008
language English
container_title Algebra and Discrete Mathematics
publisher Інститут прикладної математики і механіки НАН України
format Article
description Let Tn(x) be the degree-n Chebyshev polynomial of the first kind. It is known [1,13] that Tp(x)≡xpmodp, when p is an odd prime, and therefore, Tp(a)≡amodp for all a. Our main result is the characterization of composite numbers n satisfying the condition Tn(a)≡amodn, for any integer a. We call these pseudoprimes Chebyshev numbers, and show that n is a Chebyshev number if and only if n is odd, squarefree, and for each of its prime divisors p, n≡±1modp−1 and n≡±1modp+1. Like Carmichael numbers, they must be the product of at least three primes. Our computations show there is one Chebyshev number less than 10¹⁰, although it is reasonable to expect there are infinitely many. Our proofs are based on factorization and resultant properties of Chebyshev polynomials.
issn 1726-3255
url https://nasplib.isofts.kiev.ua/handle/123456789/152391
citation_txt Characterization of Chebyshev Numbers / D.P. Jacobs, V. Trevisan, M.O. Rayers // Algebra and Discrete Mathematics. — 2008. — Vol. 7, № 2. — С. 65–82. — Бібліогр.: 17 назв. — англ.
work_keys_str_mv AT jacobsdp characterizationofchebyshevnumbers
AT trevisanv characterizationofchebyshevnumbers
AT rayersmo characterizationofchebyshevnumbers
first_indexed 2025-12-07T20:29:06Z
last_indexed 2025-12-07T20:29:06Z
_version_ 1850882755756294144