cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A346209 Number of n X n matrices over GF(3) with no eigenvalues in GF(3), i.e., neither 0 nor 1 nor 2 is an eigenvalue.

Original entry on oeis.org

1, 0, 18, 3456, 7619508, 149200289280, 26394940582090344, 42062797470468915399168, 603463180651533072058654437264, 77927374189849689541269666899007713280, 90570450400853976077932766909301405665963077152
Offset: 0

Views

Author

Geoffrey Critzer, Jul 10 2021

Keywords

Comments

Equivalently, a(n) is the number of n X n matrices over GF(3) whose characteristic polynomial has no linear factors.

Crossrefs

Programs

  • Mathematica
    nn = 10; q = 3; \[Nu] = Table[1/n Sum[MoebiusMu[n/d] q^d, {d, Divisors[n]}], {n, 1, nn}];Table[Product[q^n - q^i, {i, 0, n - 1}], {n, 0, nn}] CoefficientList[Series[Product[Product[1/(1 - u^d/q^(r d)), {r, 1, \[Infinity]}]^\[Nu][[d]], {d, 2, nn}], {u, 0, nn}], u]

Formula

Sum_{n>=0} a(n)*x^n/A053290(n) = Product_{d>=2} (Product_{r>=1} 1/(1-x^d/3^(r*d)))^A027376(d).

A378666 Triangular array read by rows: T(n,k) is the number of n X n idempotent matrices over GF(3) having rank k, n>=0, 0<=k<=n.

Original entry on oeis.org

1, 1, 1, 1, 12, 1, 1, 117, 117, 1, 1, 1080, 10530, 1080, 1, 1, 9801, 882090, 882090, 9801, 1, 1, 88452, 72243171, 666860040, 72243171, 88452, 1, 1, 796797, 5873190687, 491992666011, 491992666011, 5873190687, 796797, 1, 1, 7173360, 476309310660, 360089838858960, 3267815287645062, 360089838858960, 476309310660, 7173360, 1
Offset: 0

Views

Author

Geoffrey Critzer, Dec 02 2024

Keywords

Comments

A matrix M is idempotent if M^2 = M.

Examples

			Triangle T(n,k) begins:
  1;
  1,    1;
  1,   12,      1;
  1,  117,    117,      1;
  1, 1080,  10530,   1080,    1;
  1, 9801, 882090, 882090, 9801, 1;
  ...
		

Crossrefs

Cf. A296548, A053846 (row sums).

Programs

  • Maple
    b:= proc(n, k) option remember; `if`(k<0 or k>n, 0,
          `if`(n=0, 1, b(n-1, k-1)+3^k*b(n-1, k)))
        end:
    T:= (n,k)-> 3^(k*(n-k))*b(n, k):
    seq(seq(T(n,k), k=0..n), n=0..8);  # Alois P. Heinz, Dec 02 2024
  • Mathematica
    nn = 8; \[Gamma][n_, q_] := Product[q^n - q^i, {i, 0, n - 1}]; B[n_, q_] := \[Gamma][n, q]/(q - 1)^n; \[Zeta][x_] := Sum[x^n/B[n, 3], {n, 0, nn}];Map[Select[#, # > 0 &] &, Table[B[n, 3], {n,0,nn}]*CoefficientList[Series[\[Zeta][x] \[Zeta][y x], {x, 0, nn}], {x, y}]] // Flatten

Formula

Sum_{n>=0} Sum_{k=0..n} T(n,k)*y^k*x^n/B(n) = e(x)*e(y*x) where e(x) = Sum_{n>=0} x^n/B(n) and B(n) = A053290(n)/2^n.
T(n,k) = A022167(n,k) * A118180(n,k). - Alois P. Heinz, Dec 02 2024

A086087 a(n) is the minimal m such that the group GL(m,3) has an element of order n.

Original entry on oeis.org

1, 2, 2, 4, 2, 6, 2, 4, 4, 5, 4, 3, 6, 6, 4, 16, 4, 18, 4, 8, 5, 11, 4
Offset: 2

Views

Author

Yuval Dekel (dekelyuval(AT)hotmail.com), Aug 24 2003

Keywords

Comments

For n > 2, a(prime(n)) = A062117(n). Also, for any n, a(n) <= n. - Eric M. Schmidt, May 18 2013

Crossrefs

Programs

  • GAP
    A086087 := function(n) local m; if IsPrime(n) and n>3 then return Order(3*Z(n)^0); fi; m := 1; while true do if ForAny(ConjugacyClasses(GL(m, 3)), cc->Order(Representative(cc))=n) then return m; fi; m := m + 1; od; end; # Eric M. Schmidt, May 18 2013

Extensions

Extended and corrected by Eric M. Schmidt, May 18 2013

A086752 Number of n X n matrices over GF(3) with rank n-1.

Original entry on oeis.org

1, 32, 8112, 17971200, 355207057920, 63010655570903040, 100505356319291594711040, 1442361950110091891786121216000, 186276322602412236974585775503690956800, 216505458700483736766078241517019274701019545600, 2264736353104098912130003755084217747715114856943819161600
Offset: 1

Views

Author

Yuval Dekel (dekelyuval(AT)hotmail.com), Jul 31 2003

Keywords

Crossrefs

Programs

  • Mathematica
    Table[3^(n^2) * (1 - 1/3^n) * QPochhammer[1/3^n, 3, n-1]/2, {n, 1, 10}] (* Vaclav Kotesovec, Apr 14 2024 *)

Formula

For n>=2: a(n) = Product_{j=0..n-2} (3^n - 3^j)^2 / (3^(n-1)- 3^j).
a(n) = ((3^n-1)/2)*Product_{j=0..n-2} (3^n-3^j). - David Wasserman, Mar 28 2005

Extensions

More terms from David Wasserman, Mar 28 2005

A220790 Product(6^n - 6^k, k=0..n-1).

Original entry on oeis.org

1, 5, 1050, 8127000, 2273284440000, 22906523331216000000, 8310241106635054164480000000, 108537128570336598656772717772800000000, 51032497739317419104816901041614046625792000000000
Offset: 0

Views

Author

Vincenzo Librandi, Jan 28 2013

Keywords

Crossrefs

Sequences given by product(m^n-m^k, k=0..n-1): A002884 (m=2), A053290 (m=3), A053291 (m=4), A053292 (m=5), A053293 (m=7), A052496 (m=8), A052497 (m=9), A052498 (m=11).

Programs

  • Magma
    [1] cat [&*[(6^n - 6^k): k in [0..n-1]]: n in [1..8]]; // Bruno Berselli, Jan 28 2013
    
  • Magma
    /* By the second formula: */
    m:=9;
    A109354 := [6^(n*(n-1) div 2): n in [0..m-1]];
    A027873 := [1] cat [&*[6^i-1: i in [1..n]]: n in [1..m]];
    [A109354[i]*A027873[i]: i in [1..m]]; // Bruno Berselli, Jan 30 2013
  • Mathematica
    Table[Product[6^n - 6^k, {k, 0, n-1}], {n, 0, 60}]

Formula

a(n) = (6^n - 1)*(6^n - 6)*...*(6^n - 6^(n-1)) for n>0, a(0)=1.
a(n) = A109354(n)*A027873(n). - Bruno Berselli, Jan 30 2013

A220791 Number of nonsingular n X n matrices over GF(13).

Original entry on oeis.org

1, 12, 26208, 9726417792, 610296923230525440, 6471875909051511775903457280, 11598637276362103019770723830073032376320, 3512938445418644176053176560741858449740612202579886080
Offset: 0

Views

Author

Vincenzo Librandi, Jan 29 2013

Keywords

Crossrefs

Programs

  • Magma
    [1] cat [&*[(13^n - 13^k): k in [0..n-1]]: n in [1..8]];
  • Mathematica
    Table[Product[13^n - 13^k, {k, 0, n-1}], {n, 0, 8}]

A053995 Bases of n-dimensional vector space over GF(3).

Original entry on oeis.org

1, 2, 24, 1872, 1010880, 3963053952, 116846682720768, 26600881786245651456, 47704425342545776582103040, 684471586202557775548246032261120, 79552147744537053441626504660608566263808, 75648987817302293231984664268437958161057494925312
Offset: 0

Views

Author

Vladeta Jovovic, Apr 05 2000

Keywords

Crossrefs

Formula

a(n) = (3^n-1)(3^n-3)...(3^n-3^(n-1))/n!.
From Geoffrey Critzer, Sep 27 2022: (Start)
Sum_{n>=0} a(n)*x^n/A053290(n) = exp(x).
a(n) = A053290(n) / n!. (End)

A297892 Triangle read by rows. T(n,k) is the number of n X n diagonalizable matrices over GF(3) that have rank k, 0 <= k <= n, n >= 0.

Original entry on oeis.org

1, 1, 2, 1, 24, 14, 1, 234, 1638, 236, 1, 2160, 147420, 254880, 12692, 1, 19602, 12349260, 208173240, 124394292, 1783784, 1, 176904, 1011404394, 157378969440, 916910326332, 157779262368, 811523288
Offset: 0

Views

Author

Geoffrey Critzer, Jan 07 2018

Keywords

Examples

			Triangle begins
  1;
  1,     2;
  1,    24,       14;
  1,   234,     1638,       236;
  1,  2160,   147420,    254880,     12692;
  1, 19602, 12349260, 208173240, 124394292, 1783784;
		

Crossrefs

Cf. A296548, A053846 (main diagonal), A290516 (row sums).

Programs

  • Mathematica
    nn = 5; g[n_] := (q - 1)^n  q^Binomial[n, 2] FunctionExpand[QFactorial[n, q]] /. q -> 3;G[n] := Sum[u z^r/g[r], {r, 0, nn}]; Grid[Map[Select[#, # > 0 &] &,Table[g[n], {n, 0, nn}] CoefficientList[Series[Sum[(u z)^r/g[r] , {r, 0, nn}]^2 Sum[
           z^r/g[r], {r, 0, nn}], {z, 0, nn}], {z, u}]]]

Formula

T(n,k)/A053290(n) is the coefficient of y^k*x^n in the expansion of Sum_{n>=0} x^n\A053290(n) * (Sum_{n>=0} y*x^n\A053290(n))^2.

A335384 Order of the finite groups GL(m,q) [or GL_m(q)] in increasing order as q runs through the prime powers.

Original entry on oeis.org

6, 48, 168, 180, 480, 2016, 3528, 5760, 11232, 13200, 20160, 26208, 61200, 78336, 123120, 181440, 267168, 374400, 511056, 682080, 892800, 1014816, 1488000, 1822176, 2755200, 3337488, 4773696, 5644800, 7738848, 9999360, 11908560, 13615200, 16511040, 19845936, 24261120, 25048800, 28003968
Offset: 1

Views

Author

Bernard Schott, Jun 04 2020

Keywords

Comments

GL(m,q) is the general linear group, the group of invertible m X m matrices over the finite field F_q with q = p^k elements.
By definition, all fields must contain at least two distinct elements, so q >= 2. As GL(1,q) is isomorphic to F_q*, the multiplicative group [whose order is p^k-1 (A181062)] of finite field F_q, data begins with m >= 2.
Some isomorphisms (let "==" denote "isomorphic to"):
a(1) = 6 for GL(2,2) == PSL(2,2) == S_3.
a(2) = 48 for GL(2,3) that has 55 subgroups.
a(3) = 168 for GL(3,2) == PSL(2,7) [A031963].
a(11) = 20160 for GL(4,2) == PSL(4,2) == Alt(8).
Array for order of GL(m,q) begins:
=============================================================
m\q | 2 3 4=2^2 5 7
-------------------------------------------------------------
2 | 6 48 180 480 2016
3 | 168 11232 181440 1488000 33784128
4 | 20160 24261120 2961100800 116064000000 #GL(4,7)
5 |9999360 #GL(5,3) ... ... ...

Examples

			a(1) = #GL(2,2) = (2^2-1)*(2^2-2) = 3*2 = 6 and the 6 elements of GL(2,2) that is isomorphic to S_3 are the 6 following 2 X 2 invertible matrices with entries in F_2:
  (1 0)   (1 1)   (1 0)   (0 1)   (0 1)   (1 1)
  (0 1) , (0 1) , (1 1) , (1 0) , (1 1) , (1 0).
a(2) = #GL(2,3) = (3^2-1)*(3^2-3) = 8*6 = 48.
a(3) = #GL(3,2) = (2^3-1)*(2^3-2)*(2^3-2^2) = 168.
		

References

  • J. H. Conway, R. T. Curtis, S. P. Norton, R. A. Parker and R. A. Wilson, ATLAS of Finite Groups. Oxford Univ. Press, 1985 [for best online version see https://oeis.org/wiki/Welcome#Links_to_Other_Sites].
  • Daniel Perrin, Cours d'Algèbre, Maths Agreg, Ellipses, 1996, pages 95-115.

Crossrefs

Cf. A059238 [GL(2,q)].
Cf. A002884 [GL(m,2)], A053290 [GL(m,3)], A053291 [GL(m,4)], A053292 [GL(m,5)], A053293 [GL(m,7)], A052496 [GL(m,8)], A052497 [GL(m,9)], A052498 [GL(m,11)].
Cf. A316622 [GL(n,Z_k)].

Formula

#GL(m,q) = Product_{k=0..m-1}(q^m-q^k).

A346384 Triangle read by rows. T(n,k) is the number of invertible n X n matrices over GF(3) such that the dimension of the eigenspace corresponding to the eigenvalue 1 is k, 0 <= k <= n, n >= 0.

Original entry on oeis.org

1, 1, 1, 27, 20, 1, 6291, 4719, 221, 1, 13589289, 10191960, 477750, 2120, 1, 266377183929, 199782888129, 9364822830, 41559870, 19481, 1, 47123189360124723, 35342392020078780, 1656674625945339, 7352106327720, 3446299857, 176540, 1
Offset: 0

Views

Author

Geoffrey Critzer, Jul 14 2021

Keywords

Examples

			             1;
             1,            1;
            27,           20,          1;
          6291,         4719,        221,        1;
      13589289,     10191960,     477750,     2120,     1;
  266377183929, 199782888129, 9364822830, 41559870, 19481, 1;
		

Crossrefs

Cf. A051680 (column k=0), A053290 (row sums).

Programs

  • Mathematica
    nn = 6; q = 3; b[p_, i_] := Count[p, i]; d[p_, i_] :=  Sum[j b[p, j], {j, 1, i}] + i Sum[b[p, j], {j, i + 1, Total[p]}]; aut[deg_, p_] :=  Product[Product[
       q^(d[p, i] deg) - q^((d[p, i] - k) deg), {k, 1, b[p, i]}], {i, 1, Total[p]}]; A027376 = Table[1/n Sum[MoebiusMu[n/d] q^d, {d, Divisors[n]}], {n, 1, nn}];
    g[u_, v_] := Total[Map[v^Length[#] u^Total[#]/aut[1, #] &, Level[Table[IntegerPartitions[n], {n, 0, nn}], {2}]]]; Map[Select[#, # > 0 &] &, Table[Product[q^n - q^i, {i, 0, n - 1}], {n, 0,  nn}] CoefficientList[
        Series[(g[u, v] /. v -> 1)*g[u, v]* Product[Product[1/(1 - (u/q^r)^d), {r, 1, \[Infinity]}]^A027376[[d]], {d, 2, nn}], {u, 0, nn}], {u, v}]] // Grid
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