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...

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Опубліковано в: :Algebra and Discrete Mathematics
Дата:2008
Автори: Jacobs, D.P., Trevisan, V., Rayers, M.O.
Формат: Стаття
Мова:Англійська
Опубліковано: Інститут прикладної математики і механіки НАН України 2008
Онлайн доступ:https://nasplib.isofts.kiev.ua/handle/123456789/152391
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Назва журналу:Digital Library of Periodicals of National Academy of Sciences of Ukraine
Цитувати: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.

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Digital Library of Periodicals of National Academy of Sciences of Ukraine
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author Jacobs, D.P.
Trevisan, V.
Rayers, M.O.
author_facet Jacobs, D.P.
Trevisan, V.
Rayers, M.O.
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.
collection DSpace DC
container_title Algebra and Discrete Mathematics
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.
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language English
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publisher Інститут прикладної математики і механіки НАН України
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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
spellingShingle Characterization of Chebyshev Numbers
Jacobs, D.P.
Trevisan, V.
Rayers, M.O.
title Characterization of Chebyshev Numbers
title_full Characterization of Chebyshev Numbers
title_fullStr Characterization of Chebyshev Numbers
title_full_unstemmed Characterization of Chebyshev Numbers
title_short Characterization of Chebyshev Numbers
title_sort characterization of chebyshev numbers
url https://nasplib.isofts.kiev.ua/handle/123456789/152391
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