On the Number of Conjugate Classes of Derangements

The number of conjugate classes of derangements of order n is the same as the number hn of the restricted partitions with every portion greater than 1. It is also equal to the number of isotopy classes of 2×n Latin rectangles. Sometimes the exact value is necessary, while sometimes we need the appro...

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Main Authors: Wen-Wei Li, Zhong-Lin Cheng, Jia-Bao Liu
Format: Article
Language:English
Published: Wiley 2021-01-01
Series:Journal of Mathematics
Online Access:http://dx.doi.org/10.1155/2021/6023081
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author Wen-Wei Li
Zhong-Lin Cheng
Jia-Bao Liu
author_facet Wen-Wei Li
Zhong-Lin Cheng
Jia-Bao Liu
author_sort Wen-Wei Li
collection DOAJ
description The number of conjugate classes of derangements of order n is the same as the number hn of the restricted partitions with every portion greater than 1. It is also equal to the number of isotopy classes of 2×n Latin rectangles. Sometimes the exact value is necessary, while sometimes we need the approximation value. In this paper, a recursion formula of hn will be obtained and also will some elementary approximation formulae with high accuracy for hn be presented. Although we may obtain the value of hn in some computer algebra system, it is still meaningful to find an efficient way to calculate the approximate value, especially in engineering, since most people are familiar with neither programming nor CAS software. This paper is mainly for the readers who need a simple and practical formula to obtain the approximate value (without writing a program) with more accuracy, such as to compute the value in a pocket science calculator without programming function. Some methods used here can also be applied to find the fitting functions for some types of data obtained in experiments.
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spelling doaj-art-d4ba643404bc434583368b34cd2238972025-02-03T00:58:55ZengWileyJournal of Mathematics2314-47852021-01-01202110.1155/2021/6023081On the Number of Conjugate Classes of DerangementsWen-Wei Li0Zhong-Lin Cheng1Jia-Bao Liu2School of Information and MathematicsSchool of Information and MathematicsSchool of Mathematics and PhysicsThe number of conjugate classes of derangements of order n is the same as the number hn of the restricted partitions with every portion greater than 1. It is also equal to the number of isotopy classes of 2×n Latin rectangles. Sometimes the exact value is necessary, while sometimes we need the approximation value. In this paper, a recursion formula of hn will be obtained and also will some elementary approximation formulae with high accuracy for hn be presented. Although we may obtain the value of hn in some computer algebra system, it is still meaningful to find an efficient way to calculate the approximate value, especially in engineering, since most people are familiar with neither programming nor CAS software. This paper is mainly for the readers who need a simple and practical formula to obtain the approximate value (without writing a program) with more accuracy, such as to compute the value in a pocket science calculator without programming function. Some methods used here can also be applied to find the fitting functions for some types of data obtained in experiments.http://dx.doi.org/10.1155/2021/6023081
spellingShingle Wen-Wei Li
Zhong-Lin Cheng
Jia-Bao Liu
On the Number of Conjugate Classes of Derangements
Journal of Mathematics
title On the Number of Conjugate Classes of Derangements
title_full On the Number of Conjugate Classes of Derangements
title_fullStr On the Number of Conjugate Classes of Derangements
title_full_unstemmed On the Number of Conjugate Classes of Derangements
title_short On the Number of Conjugate Classes of Derangements
title_sort on the number of conjugate classes of derangements
url http://dx.doi.org/10.1155/2021/6023081
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