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Properties

Label 20.4.439...125.1
Degree $20$
Signature $(4, 8)$
Discriminant $4.399\times 10^{23}$
Root discriminant \(15.21\)
Ramified primes $3,5$
Class number $1$
Class group trivial
Galois group $C_4\times D_5$ (as 20T6)

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Show commands: Magma / Oscar / Pari/GP / SageMath

Normalized defining polynomial

Copy content comment:Define the number field
 
Copy content sage:x = polygen(QQ); K.<a> = NumberField(x^20 - 3*x^15 - 31*x^10 + 3*x^5 + 1)
 
Copy content gp:K = bnfinit(y^20 - 3*y^15 - 31*y^10 + 3*y^5 + 1, 1)
 
Copy content magma:R<x> := PolynomialRing(Rationals()); K<a> := NumberField(x^20 - 3*x^15 - 31*x^10 + 3*x^5 + 1);
 
Copy content oscar:Qx, x = polynomial_ring(QQ); K, a = number_field(x^20 - 3*x^15 - 31*x^10 + 3*x^5 + 1)
 

\( x^{20} - 3x^{15} - 31x^{10} + 3x^{5} + 1 \) Copy content Toggle raw display

Copy content comment:Defining polynomial
 
Copy content sage:K.defining_polynomial()
 
Copy content gp:K.pol
 
Copy content magma:DefiningPolynomial(K);
 
Copy content oscar:defining_polynomial(K)
 

Invariants

Degree:  $20$
Copy content comment:Degree over Q
 
Copy content sage:K.degree()
 
Copy content gp:poldegree(K.pol)
 
Copy content magma:Degree(K);
 
Copy content oscar:degree(K)
 
Signature:  $(4, 8)$
Copy content comment:Signature
 
Copy content sage:K.signature()
 
Copy content gp:K.sign
 
Copy content magma:Signature(K);
 
Copy content oscar:signature(K)
 
Discriminant:   \(439949333667755126953125\) \(\medspace = 3^{10}\cdot 5^{27}\) Copy content Toggle raw display
Copy content comment:Discriminant
 
Copy content sage:K.disc()
 
Copy content gp:K.disc
 
Copy content magma:OK := Integers(K); Discriminant(OK);
 
Copy content oscar:OK = ring_of_integers(K); discriminant(OK)
 
Root discriminant:  \(15.21\)
Copy content comment:Root discriminant
 
Copy content sage:(K.disc().abs())^(1./K.degree())
 
Copy content gp:abs(K.disc)^(1/poldegree(K.pol))
 
Copy content magma:Abs(Discriminant(OK))^(1/Degree(K));
 
Copy content oscar:OK = ring_of_integers(K); (1.0 * abs(discriminant(OK)))^(1/degree(K))
 
Galois root discriminant:  $3^{1/2}5^{27/20}\approx 15.211433151416195$
Ramified primes:   \(3\), \(5\) Copy content Toggle raw display
Copy content comment:Ramified primes
 
Copy content sage:K.disc().support()
 
Copy content gp:factor(abs(K.disc))[,1]~
 
Copy content magma:PrimeDivisors(Discriminant(OK));
 
Copy content oscar:prime_divisors(discriminant(OK))
 
Discriminant root field:  \(\Q(\sqrt{5}) \)
$\Aut(K/\Q)$:   $C_4$
Copy content comment:Automorphisms
 
Copy content sage:K.automorphisms()
 
Copy content magma:Automorphisms(K);
 
Copy content oscar:automorphism_group(K)
 
This field is not Galois over $\Q$.
This is not a CM field.
This field has no CM subfields.

Integral basis (with respect to field generator \(a\))

$1$, $a$, $a^{2}$, $a^{3}$, $a^{4}$, $a^{5}$, $a^{6}$, $\frac{1}{5}a^{7}+\frac{1}{5}a^{6}-\frac{1}{5}a^{5}-\frac{2}{5}a^{2}-\frac{2}{5}a+\frac{2}{5}$, $\frac{1}{5}a^{8}-\frac{2}{5}a^{6}+\frac{1}{5}a^{5}-\frac{2}{5}a^{3}-\frac{1}{5}a-\frac{2}{5}$, $\frac{1}{5}a^{9}-\frac{2}{5}a^{6}-\frac{2}{5}a^{5}-\frac{2}{5}a^{4}-\frac{1}{5}a-\frac{1}{5}$, $\frac{1}{5}a^{10}+\frac{1}{5}a^{5}-\frac{1}{5}$, $\frac{1}{5}a^{11}+\frac{1}{5}a^{6}-\frac{1}{5}a$, $\frac{1}{5}a^{12}-\frac{1}{5}a^{6}+\frac{1}{5}a^{5}+\frac{1}{5}a^{2}+\frac{2}{5}a-\frac{2}{5}$, $\frac{1}{5}a^{13}+\frac{2}{5}a^{6}-\frac{1}{5}a^{5}+\frac{1}{5}a^{3}+\frac{1}{5}a+\frac{2}{5}$, $\frac{1}{25}a^{14}+\frac{2}{25}a^{13}-\frac{1}{25}a^{12}-\frac{2}{25}a^{11}+\frac{1}{25}a^{10}+\frac{1}{25}a^{9}+\frac{2}{25}a^{8}-\frac{1}{25}a^{7}-\frac{2}{25}a^{6}+\frac{1}{25}a^{5}-\frac{6}{25}a^{4}-\frac{12}{25}a^{3}+\frac{6}{25}a^{2}+\frac{12}{25}a-\frac{6}{25}$, $\frac{1}{25}a^{15}-\frac{1}{25}a^{10}-\frac{8}{25}a^{5}+\frac{12}{25}$, $\frac{1}{25}a^{16}-\frac{1}{25}a^{11}-\frac{8}{25}a^{6}+\frac{12}{25}a$, $\frac{1}{25}a^{17}-\frac{1}{25}a^{12}+\frac{2}{25}a^{7}+\frac{2}{5}a^{6}-\frac{2}{5}a^{5}-\frac{8}{25}a^{2}+\frac{1}{5}a-\frac{1}{5}$, $\frac{1}{25}a^{18}-\frac{1}{25}a^{13}+\frac{2}{25}a^{8}+\frac{1}{5}a^{6}+\frac{2}{5}a^{5}-\frac{8}{25}a^{3}-\frac{2}{5}a+\frac{1}{5}$, $\frac{1}{25}a^{19}+\frac{2}{25}a^{13}-\frac{1}{25}a^{12}-\frac{2}{25}a^{11}+\frac{1}{25}a^{10}-\frac{2}{25}a^{9}+\frac{2}{25}a^{8}-\frac{1}{25}a^{7}-\frac{12}{25}a^{6}-\frac{9}{25}a^{5}-\frac{4}{25}a^{4}-\frac{12}{25}a^{3}+\frac{6}{25}a^{2}+\frac{7}{25}a-\frac{11}{25}$ Copy content Toggle raw display

Copy content comment:Integral basis
 
Copy content sage:K.integral_basis()
 
Copy content gp:K.zk
 
Copy content magma:IntegralBasis(K);
 
Copy content oscar:basis(OK)
 

Monogenic:  Not computed
Index:  $1$
Inessential primes:  None

Class group and class number

Ideal class group:  Trivial group, which has order $1$
Copy content comment:Class group
 
Copy content sage:K.class_group().invariants()
 
Copy content gp:K.clgp
 
Copy content magma:ClassGroup(K);
 
Copy content oscar:class_group(K)
 
Narrow class group:  $C_{2}$, which has order $2$
Copy content comment:Narrow class group
 
Copy content sage:K.narrow_class_group().invariants()
 
Copy content gp:bnfnarrow(K)
 
Copy content magma:NarrowClassGroup(K);
 

Unit group

Copy content comment:Unit group
 
Copy content sage:UK = K.unit_group()
 
Copy content magma:UK, fUK := UnitGroup(K);
 
Copy content oscar:UK, fUK = unit_group(OK)
 
Rank:  $11$
Copy content comment:Unit rank
 
Copy content sage:UK.rank()
 
Copy content gp:K.fu
 
Copy content magma:UnitRank(K);
 
Copy content oscar:rank(UK)
 
Torsion generator:   \( -1 \)  (order $2$) Copy content Toggle raw display
Copy content comment:Generator for roots of unity
 
Copy content sage:UK.torsion_generator()
 
Copy content gp:K.tu[2]
 
Copy content magma:K!f(TU.1) where TU,f is TorsionUnitGroup(K);
 
Copy content oscar:torsion_units_generator(OK)
 
Fundamental units:   $a$, $\frac{4}{25}a^{17}-\frac{14}{25}a^{12}-\frac{117}{25}a^{7}+\frac{58}{25}a^{2}$, $\frac{1}{5}a^{15}-\frac{3}{5}a^{10}-6a^{5}-\frac{1}{5}$, $\frac{11}{25}a^{19}-\frac{3}{25}a^{18}+\frac{2}{25}a^{17}-\frac{1}{25}a^{16}-\frac{2}{25}a^{15}-\frac{32}{25}a^{14}+\frac{11}{25}a^{13}-\frac{6}{25}a^{12}+\frac{3}{25}a^{11}+\frac{6}{25}a^{10}-\frac{344}{25}a^{9}+\frac{87}{25}a^{8}-\frac{12}{5}a^{7}+\frac{6}{5}a^{6}+\frac{12}{5}a^{5}+\frac{3}{25}a^{4}-\frac{69}{25}a^{3}+\frac{3}{25}a^{2}+\frac{11}{25}a-\frac{3}{25}$, $\frac{9}{25}a^{18}+\frac{1}{5}a^{17}-\frac{1}{5}a^{16}-\frac{29}{25}a^{13}-\frac{3}{5}a^{12}+\frac{3}{5}a^{11}-\frac{272}{25}a^{8}-\frac{31}{5}a^{7}+\frac{31}{5}a^{6}+\frac{88}{25}a^{3}+\frac{1}{5}a^{2}-\frac{1}{5}a$, $\frac{1}{25}a^{19}-\frac{7}{25}a^{18}+\frac{4}{25}a^{17}-\frac{1}{25}a^{16}-\frac{2}{25}a^{14}+\frac{4}{5}a^{13}-\frac{13}{25}a^{12}+\frac{3}{25}a^{11}-\frac{1}{25}a^{10}-\frac{34}{25}a^{9}+\frac{219}{25}a^{8}-\frac{121}{25}a^{7}+\frac{6}{5}a^{6}+\frac{4}{25}a^{5}-\frac{32}{25}a^{4}+\frac{13}{25}a^{3}+\frac{37}{25}a^{2}+\frac{11}{25}a+\frac{21}{25}$, $\frac{2}{5}a^{19}+\frac{1}{5}a^{17}-\frac{3}{25}a^{16}-\frac{6}{5}a^{14}-\frac{3}{5}a^{12}+\frac{8}{25}a^{11}-\frac{62}{5}a^{9}-\frac{31}{5}a^{7}+\frac{94}{25}a^{6}+\frac{7}{5}a^{4}+\frac{1}{5}a^{2}+\frac{29}{25}a$, $\frac{2}{5}a^{19}+\frac{2}{5}a^{18}+\frac{2}{25}a^{17}-\frac{6}{5}a^{14}-\frac{6}{5}a^{13}-\frac{7}{25}a^{12}-\frac{62}{5}a^{9}-\frac{62}{5}a^{8}-\frac{61}{25}a^{7}+\frac{7}{5}a^{4}+\frac{7}{5}a^{3}+\frac{34}{25}a^{2}$, $\frac{6}{25}a^{19}-\frac{1}{25}a^{18}+\frac{4}{25}a^{17}-\frac{2}{25}a^{16}-\frac{4}{25}a^{15}-\frac{18}{25}a^{14}+\frac{2}{25}a^{13}-\frac{12}{25}a^{12}+\frac{6}{25}a^{11}+\frac{12}{25}a^{10}-\frac{37}{5}a^{9}+\frac{34}{25}a^{8}-5a^{7}+\frac{12}{5}a^{6}+5a^{5}+\frac{19}{25}a^{4}+\frac{32}{25}a^{3}+\frac{16}{25}a^{2}-\frac{3}{25}a-\frac{16}{25}$, $\frac{7}{25}a^{19}-\frac{2}{25}a^{18}-\frac{1}{25}a^{17}+\frac{2}{25}a^{16}-\frac{1}{25}a^{15}-\frac{4}{5}a^{14}+\frac{6}{25}a^{13}+\frac{4}{25}a^{12}-\frac{6}{25}a^{11}+\frac{3}{25}a^{10}-\frac{219}{25}a^{9}+\frac{12}{5}a^{8}+\frac{26}{25}a^{7}-\frac{12}{5}a^{6}+\frac{7}{5}a^{5}-\frac{13}{25}a^{4}-\frac{3}{25}a^{3}-\frac{7}{5}a^{2}+\frac{3}{25}a+\frac{1}{25}$, $\frac{3}{25}a^{19}-\frac{4}{25}a^{17}+\frac{2}{25}a^{16}+\frac{2}{25}a^{15}-\frac{11}{25}a^{14}-\frac{1}{25}a^{13}+\frac{12}{25}a^{12}-\frac{6}{25}a^{11}-\frac{1}{5}a^{10}-\frac{87}{25}a^{9}+\frac{4}{25}a^{8}+5a^{7}-\frac{12}{5}a^{6}-\frac{64}{25}a^{5}+\frac{69}{25}a^{4}+\frac{21}{25}a^{3}-\frac{16}{25}a^{2}+\frac{3}{25}a-\frac{18}{25}$ Copy content Toggle raw display
Copy content comment:Fundamental units
 
Copy content sage:UK.fundamental_units()
 
Copy content gp:K.fu
 
Copy content magma:[K|fUK(g): g in Generators(UK)];
 
Copy content oscar:[K(fUK(a)) for a in gens(UK)]
 
Regulator:  \( 7296.61382034 \)
Copy content comment:Regulator
 
Copy content sage:K.regulator()
 
Copy content gp:K.reg
 
Copy content magma:Regulator(K);
 
Copy content oscar:regulator(K)
 
Unit signature rank:  \( 3 \)

Class number formula

\[ \begin{aligned}\lim_{s\to 1} (s-1)\zeta_K(s) =\mathstrut & \frac{2^{r_1}\cdot (2\pi)^{r_2}\cdot R\cdot h}{w\cdot\sqrt{|D|}}\cr \approx\mathstrut &\frac{2^{4}\cdot(2\pi)^{8}\cdot 7296.61382034 \cdot 1}{2\cdot\sqrt{439949333667755126953125}}\cr\approx \mathstrut & 0.213771085813 \end{aligned}\]

Copy content comment:Analytic class number formula
 
Copy content sage:# self-contained SageMath code snippet to compute the analytic class number formula x = polygen(QQ); K.<a> = NumberField(x^20 - 3*x^15 - 31*x^10 + 3*x^5 + 1) DK = K.disc(); r1,r2 = K.signature(); RK = K.regulator(); RR = RK.parent() hK = K.class_number(); wK = K.unit_group().torsion_generator().order(); 2^r1 * (2*RR(pi))^r2 * RK * hK / (wK * RR(sqrt(abs(DK))))
 
Copy content gp:\\ self-contained Pari/GP code snippet to compute the analytic class number formula K = bnfinit(x^20 - 3*x^15 - 31*x^10 + 3*x^5 + 1, 1); [polcoeff (lfunrootres (lfuncreate (K))[1][1][2], -1), 2^K.r1 * (2*Pi)^K.r2 * K.reg * K.no / (K.tu[1] * sqrt (abs (K.disc)))]
 
Copy content magma:/* self-contained Magma code snippet to compute the analytic class number formula */ Qx<x> := PolynomialRing(Rationals()); K<a> := NumberField(x^20 - 3*x^15 - 31*x^10 + 3*x^5 + 1); OK := Integers(K); DK := Discriminant(OK); UK, fUK := UnitGroup(OK); clK, fclK := ClassGroup(OK); r1,r2 := Signature(K); RK := Regulator(K); RR := Parent(RK); hK := #clK; wK := #TorsionSubgroup(UK); 2^r1 * (2*Pi(RR))^r2 * RK * hK / (wK * Sqrt(RR!Abs(DK)));
 
Copy content oscar:# self-contained Oscar code snippet to compute the analytic class number formula Qx, x = polynomial_ring(QQ); K, a = number_field(x^20 - 3*x^15 - 31*x^10 + 3*x^5 + 1); OK = ring_of_integers(K); DK = discriminant(OK); UK, fUK = unit_group(OK); clK, fclK = class_group(OK); r1,r2 = signature(K); RK = regulator(K); RR = parent(RK); hK = order(clK); wK = torsion_units_order(K); 2^r1 * (2*pi)^r2 * RK * hK / (wK * sqrt(RR(abs(DK))))
 

Galois group

$C_4\times D_5$ (as 20T6):

Copy content comment:Galois group
 
Copy content sage:K.galois_group()
 
Copy content gp:polgalois(K.pol)
 
Copy content magma:G = GaloisGroup(K);
 
Copy content oscar:G, Gtx = galois_group(K); degree(K) > 1 ? (G, transitive_group_identification(G)) : (G, nothing)
 
A solvable group of order 40
The 16 conjugacy class representatives for $C_4\times D_5$
Character table for $C_4\times D_5$

Intermediate fields

\(\Q(\sqrt{5}) \), \(\Q(\zeta_{15})^+\), 5.1.140625.1, 10.2.98876953125.1

Fields in the database are given up to isomorphism. Isomorphic intermediate fields are shown with their multiplicities.

Copy content comment:Intermediate fields
 
Copy content sage:K.subfields()[1:-1]
 
Copy content gp:L = nfsubfields(K); L[2..length(L)]
 
Copy content magma:L := Subfields(K); L[2..#L];
 
Copy content oscar:subfields(K)[2:end-1]
 

Sibling fields

Galois closure: data not computed
Degree 20 sibling: 20.0.48883259296417236328125.1
Minimal sibling: 20.0.48883259296417236328125.1

Frobenius cycle types

$p$ $2$ $3$ $5$ $7$ $11$ $13$ $17$ $19$ $23$ $29$ $31$ $37$ $41$ $43$ $47$ $53$ $59$
Cycle type $20$ R R ${\href{/padicField/7.4.0.1}{4} }^{5}$ ${\href{/padicField/11.2.0.1}{2} }^{10}$ ${\href{/padicField/13.4.0.1}{4} }^{5}$ $20$ ${\href{/padicField/19.10.0.1}{10} }^{2}$ $20$ ${\href{/padicField/29.2.0.1}{2} }^{8}{,}\,{\href{/padicField/29.1.0.1}{1} }^{4}$ ${\href{/padicField/31.5.0.1}{5} }^{4}$ ${\href{/padicField/37.4.0.1}{4} }^{5}$ ${\href{/padicField/41.2.0.1}{2} }^{10}$ ${\href{/padicField/43.4.0.1}{4} }^{5}$ $20$ $20$ ${\href{/padicField/59.2.0.1}{2} }^{8}{,}\,{\href{/padicField/59.1.0.1}{1} }^{4}$

In the table, R denotes a ramified prime. Cycle lengths which are repeated in a cycle type are indicated by exponents.

Copy content comment:Frobenius cycle types
 
Copy content sage:# to obtain a list of [e_i,f_i] for the factorization of the ideal pO_K for p=7 in Sage: p = 7; [(e, pr.norm().valuation(p)) for pr,e in K.factor(p)]
 
Copy content gp:\\ to obtain a list of [e_i,f_i] for the factorization of the ideal pO_K for p=7 in Pari: p = 7; pfac = idealprimedec(K, p); vector(length(pfac), j, [pfac[j][3], pfac[j][4]])
 
Copy content magma:// to obtain a list of [e_i,f_i] for the factorization of the ideal pO_K for p=7 in Magma: p := 7; [<pr[2], Valuation(Norm(pr[1]), p)> : pr in Factorization(p*Integers(K))];
 
Copy content oscar:# to obtain a list of [e_i,f_i] for the factorization of the ideal pO_K for p=7 in Oscar: p = 7; pfac = factor(ideal(ring_of_integers(K), p)); [(e, valuation(norm(pr),p)) for (pr,e) in pfac]
 

Local algebras for ramified primes

$p$LabelPolynomial $e$ $f$ $c$ Galois group Slope content
\(3\) Copy content Toggle raw display 3.2.2.2a1.1$x^{4} + 4 x^{3} + 8 x^{2} + 11 x + 4$$2$$2$$2$$C_4$$$[\ ]_{2}^{2}$$
3.4.2.4a1.2$x^{8} + 4 x^{7} + 4 x^{6} + 4 x^{4} + 8 x^{3} + 7$$2$$4$$4$$C_4\times C_2$$$[\ ]_{2}^{4}$$
3.4.2.4a1.2$x^{8} + 4 x^{7} + 4 x^{6} + 4 x^{4} + 8 x^{3} + 7$$2$$4$$4$$C_4\times C_2$$$[\ ]_{2}^{4}$$
\(5\) Copy content Toggle raw display 5.1.20.27a4.7$x^{20} + 15 x^{8} + 20$$20$$1$$27$not computednot computed

Spectrum of ring of integers

(0)(0)(2)(3)(5)(7)(11)(13)(17)(19)(23)(29)(31)(37)(41)(43)(47)(53)(59)