Properties

Label 21T2
Degree $21$
Order $21$
Cyclic no
Abelian no
Solvable yes
Primitive no
$p$-group no
Group: $C_7:C_3$

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Show commands: Magma

magma: G := TransitiveGroup(21, 2);
 

Group action invariants

Degree $n$:  $21$
magma: t, n := TransitiveGroupIdentification(G); n;
 
Transitive number $t$:  $2$
magma: t, n := TransitiveGroupIdentification(G); t;
 
Group:  $C_7:C_3$
Parity:  $1$
magma: IsEven(G);
 
Primitive:  no
magma: IsPrimitive(G);
 
magma: NilpotencyClass(G);
 
$\card{\Aut(F/K)}$:  $21$
magma: Order(Centralizer(SymmetricGroup(n), G));
 
Generators:  (1,5,10)(2,6,11)(3,4,12)(7,16,13)(8,17,14)(9,18,15)(19,20,21), (1,4,7,11,14,18,19)(2,5,8,12,15,16,20)(3,6,9,10,13,17,21)
magma: Generators(G);
 

Low degree resolvents

|G/N|Galois groups for stem field(s)
$3$:  $C_3$

Resolvents shown for degrees $\leq 47$

Subfields

Degree 3: $C_3$

Degree 7: $C_7:C_3$

Low degree siblings

7T3

Siblings are shown with degree $\leq 47$

A number field with this Galois group has no arithmetically equivalent fields.

Conjugacy classes

LabelCycle TypeSizeOrderRepresentative
$ 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 $ $1$ $1$ $()$
$ 3, 3, 3, 3, 3, 3, 3 $ $7$ $3$ $( 1, 2, 3)( 4, 8,13)( 5, 9,14)( 6, 7,15)(10,19,16)(11,20,17)(12,21,18)$
$ 3, 3, 3, 3, 3, 3, 3 $ $7$ $3$ $( 1, 3, 2)( 4,13, 8)( 5,14, 9)( 6,15, 7)(10,16,19)(11,17,20)(12,18,21)$
$ 7, 7, 7 $ $3$ $7$ $( 1, 4, 7,11,14,18,19)( 2, 5, 8,12,15,16,20)( 3, 6, 9,10,13,17,21)$
$ 7, 7, 7 $ $3$ $7$ $( 1,11,19, 7,18, 4,14)( 2,12,20, 8,16, 5,15)( 3,10,21, 9,17, 6,13)$

magma: ConjugacyClasses(G);
 

Group invariants

Order:  $21=3 \cdot 7$
magma: Order(G);
 
Cyclic:  no
magma: IsCyclic(G);
 
Abelian:  no
magma: IsAbelian(G);
 
Solvable:  yes
magma: IsSolvable(G);
 
Nilpotency class:   not nilpotent
Label:  21.1
magma: IdentifyGroup(G);
 
Character table:

1A 3A1 3A-1 7A1 7A-1
Size 1 7 7 3 3
3 P 1A 3A-1 3A1 7A1 7A-1
7 P 1A 1A 1A 7A-1 7A1
Type
21.1.1a R 1 1 1 1 1
21.1.1b1 C 1 ζ31 ζ3 1 1
21.1.1b2 C 1 ζ3 ζ31 1 1
21.1.3a1 C 3 0 0 ζ731ζ7ζ72 ζ73+ζ7+ζ72
21.1.3a2 C 3 0 0 ζ73+ζ7+ζ72 ζ731ζ7ζ72

magma: CharacterTable(G);