Groups of order 65: Difference between revisions

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{{groups of order|65}}
{{groups of order|65}}


Up to isomorphism, there is a ''unique'' group of order 15, namely [[cyclic group:Z65]], which is also the [[external direct product]] of [[cyclic group:Z5]] and [[cyclic group:Z13]].
Up to isomorphism, there is a ''unique'' group of order 65, namely [[cyclic group:Z65]], which is also the [[external direct product]] of [[cyclic group:Z5]] and [[cyclic group:Z13]].


The fact of uniqueness follows from the [[classification of groups of order a product of two distinct primes]]. Since <math>15 = 5 \cdot 13</math> and <math>5</math> does not divide <math>(13 - 1)</math>, the number <math>65</math> falls in the ''one isomorphism class'' case.
The fact of uniqueness follows from the [[classification of groups of order a product of two distinct primes]]. Since <math>15 = 5 \cdot 13</math> and <math>5</math> does not divide <math>(13 - 1)</math>, the number <math>65</math> falls in the ''one isomorphism class'' case.


Another way of viewing this is that <math>65</math> is a [[cyclicity-forcing number]], i.e., any group of order 65 is cyclic. See the [[classification of cyclicity-forcing numbers]] to see the necessary and sufficient condition for a natural number to be cyclicity-forcing.
Another way of viewing this is that <math>65</math> is a [[cyclicity-forcing number]], i.e., any group of order 65 is cyclic. See the [[classification of cyclicity-forcing numbers]] to see the necessary and sufficient condition for a natural number to be cyclicity-forcing.

Latest revision as of 10:50, 22 October 2023

This article gives information about, and links to more details on, groups of order 65
See pages on algebraic structures of order 65 | See pages on groups of a particular order

Up to isomorphism, there is a unique group of order 65, namely cyclic group:Z65, which is also the external direct product of cyclic group:Z5 and cyclic group:Z13.

The fact of uniqueness follows from the classification of groups of order a product of two distinct primes. Since 15=513 and 5 does not divide (131), the number 65 falls in the one isomorphism class case.

Another way of viewing this is that 65 is a cyclicity-forcing number, i.e., any group of order 65 is cyclic. See the classification of cyclicity-forcing numbers to see the necessary and sufficient condition for a natural number to be cyclicity-forcing.