Classify all groups of order 4165
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Classify all groups of order $4165=5(7^2)17$
I've determined the following possibilities for each of the sylow subgroups
$r_5 = 1$
$r_7 = 1$ or $5(17)$
$r_17 = 1$ or $5(7)$
I'm trying to show either the sylow 7 subgroup or the sylow 17 subgroup is normal so that I can create a subgroup of index 5. Then I would use semi-direct product theorem. But maybe this is not necessary and maybe there is a simpler solution.
abstract-algebra group-theory finite-groups
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up vote
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down vote
favorite
Classify all groups of order $4165=5(7^2)17$
I've determined the following possibilities for each of the sylow subgroups
$r_5 = 1$
$r_7 = 1$ or $5(17)$
$r_17 = 1$ or $5(7)$
I'm trying to show either the sylow 7 subgroup or the sylow 17 subgroup is normal so that I can create a subgroup of index 5. Then I would use semi-direct product theorem. But maybe this is not necessary and maybe there is a simpler solution.
abstract-algebra group-theory finite-groups
2
None of $7, 7^2$ or $7^2cdot17$ are $equiv1pmod5$, so it looks like you have a normal Sylow $5$
– Jyrki Lahtonen
17 mins ago
Only $7^2cdot 17$ is 1 mod 5
– iYOA
15 mins ago
2
$7cdot7cdot17equiv2cdot2cdot2=8equiv3pmod5$.
– Jyrki Lahtonen
14 mins ago
1
And the automorphism group of $C_5$ is $simeq C_4$, so that Sylow $5$-subgroup must be central.
– Jyrki Lahtonen
12 mins ago
wow...I can't do arithmetic
– iYOA
11 mins ago
 |Â
show 2 more comments
up vote
1
down vote
favorite
up vote
1
down vote
favorite
Classify all groups of order $4165=5(7^2)17$
I've determined the following possibilities for each of the sylow subgroups
$r_5 = 1$
$r_7 = 1$ or $5(17)$
$r_17 = 1$ or $5(7)$
I'm trying to show either the sylow 7 subgroup or the sylow 17 subgroup is normal so that I can create a subgroup of index 5. Then I would use semi-direct product theorem. But maybe this is not necessary and maybe there is a simpler solution.
abstract-algebra group-theory finite-groups
Classify all groups of order $4165=5(7^2)17$
I've determined the following possibilities for each of the sylow subgroups
$r_5 = 1$
$r_7 = 1$ or $5(17)$
$r_17 = 1$ or $5(7)$
I'm trying to show either the sylow 7 subgroup or the sylow 17 subgroup is normal so that I can create a subgroup of index 5. Then I would use semi-direct product theorem. But maybe this is not necessary and maybe there is a simpler solution.
abstract-algebra group-theory finite-groups
edited 3 mins ago
asked 24 mins ago
iYOA
40339
40339
2
None of $7, 7^2$ or $7^2cdot17$ are $equiv1pmod5$, so it looks like you have a normal Sylow $5$
– Jyrki Lahtonen
17 mins ago
Only $7^2cdot 17$ is 1 mod 5
– iYOA
15 mins ago
2
$7cdot7cdot17equiv2cdot2cdot2=8equiv3pmod5$.
– Jyrki Lahtonen
14 mins ago
1
And the automorphism group of $C_5$ is $simeq C_4$, so that Sylow $5$-subgroup must be central.
– Jyrki Lahtonen
12 mins ago
wow...I can't do arithmetic
– iYOA
11 mins ago
 |Â
show 2 more comments
2
None of $7, 7^2$ or $7^2cdot17$ are $equiv1pmod5$, so it looks like you have a normal Sylow $5$
– Jyrki Lahtonen
17 mins ago
Only $7^2cdot 17$ is 1 mod 5
– iYOA
15 mins ago
2
$7cdot7cdot17equiv2cdot2cdot2=8equiv3pmod5$.
– Jyrki Lahtonen
14 mins ago
1
And the automorphism group of $C_5$ is $simeq C_4$, so that Sylow $5$-subgroup must be central.
– Jyrki Lahtonen
12 mins ago
wow...I can't do arithmetic
– iYOA
11 mins ago
2
2
None of $7, 7^2$ or $7^2cdot17$ are $equiv1pmod5$, so it looks like you have a normal Sylow $5$
– Jyrki Lahtonen
17 mins ago
None of $7, 7^2$ or $7^2cdot17$ are $equiv1pmod5$, so it looks like you have a normal Sylow $5$
– Jyrki Lahtonen
17 mins ago
Only $7^2cdot 17$ is 1 mod 5
– iYOA
15 mins ago
Only $7^2cdot 17$ is 1 mod 5
– iYOA
15 mins ago
2
2
$7cdot7cdot17equiv2cdot2cdot2=8equiv3pmod5$.
– Jyrki Lahtonen
14 mins ago
$7cdot7cdot17equiv2cdot2cdot2=8equiv3pmod5$.
– Jyrki Lahtonen
14 mins ago
1
1
And the automorphism group of $C_5$ is $simeq C_4$, so that Sylow $5$-subgroup must be central.
– Jyrki Lahtonen
12 mins ago
And the automorphism group of $C_5$ is $simeq C_4$, so that Sylow $5$-subgroup must be central.
– Jyrki Lahtonen
12 mins ago
wow...I can't do arithmetic
– iYOA
11 mins ago
wow...I can't do arithmetic
– iYOA
11 mins ago
 |Â
show 2 more comments
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2
None of $7, 7^2$ or $7^2cdot17$ are $equiv1pmod5$, so it looks like you have a normal Sylow $5$
– Jyrki Lahtonen
17 mins ago
Only $7^2cdot 17$ is 1 mod 5
– iYOA
15 mins ago
2
$7cdot7cdot17equiv2cdot2cdot2=8equiv3pmod5$.
– Jyrki Lahtonen
14 mins ago
1
And the automorphism group of $C_5$ is $simeq C_4$, so that Sylow $5$-subgroup must be central.
– Jyrki Lahtonen
12 mins ago
wow...I can't do arithmetic
– iYOA
11 mins ago