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On an Identity Relating to Partitions and Repetitions of Parts

Published online by Cambridge University Press:  20 November 2018

M. S. Kirdar
Affiliation:
University of Birmingham, Birmingham, England
T. H. R. Skyrme
Affiliation:
University of Birmingham, Birmingham, England
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This note is concerned with a simple but rather surprising identity which emerged unexpectedly from the work of one of the authors on the characterisation of characters. Consider, for example, the seven partitions of 5. These are

(1) 5, 4 1, 3 2, 3 12, 22 1, 2 13, 15

and with each of these we can associate a product of factorials of the numbers of repetitions, respectively

(2) 1!, (1!)(1!), (1!)(1!), (1!)(2!), (2!)(1!), (1!)(3!), 5!

It is then seen that the product of all the numbers occurring in (1) coincides with that of all the numbers in (2).

Generally, for any particular natural number n, the partitions can be written in the form

1a1 2a2 3a3…,

in which ak is the frequency of repetition of the part k, and are enumerated by the distinct sets {α} = {a1, a2, …,} with ak ≧ 0 and Σkak = n.

Type
Research Article
Copyright
Copyright © Canadian Mathematical Society 1982

References

1. Kirdar, M. S., On the factor group of integer-valued class functions modulo the group of the generalized characters, in preparation.Google Scholar