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.

Showing 1-10 of 31 results. Next

A047656 a(n) = 3^((n^2-n)/2).

Original entry on oeis.org

1, 1, 3, 27, 729, 59049, 14348907, 10460353203, 22876792454961, 150094635296999121, 2954312706550833698643, 174449211009120179071170507, 30903154382632612361920641803529, 16423203268260658146231467800709255289, 26183890704263137277674192438430182020124347
Offset: 0

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Author

Keywords

Comments

The number of outcomes of a chess tournament with n players.
For n >= 1, a(n) is the size of the Sylow 3-subgroup of the Chevalley group A_n(3) (sequence A053290). - Ahmed Fares (ahmedfares(AT)my-deja.com), Apr 30 2001
The number of binary relations on an n-element set that are both reflexive and antisymmetric. - Justin Witt (justinmwitt(AT)gmail.com), Jul 12 2005
The sequence a(n+1) = [1,3,27,729,59049,14348907,...] is the Hankel transform (see A001906 for definition) of A047891 = 1, 3, 12, 57, 300, 1586, 9912, ... . - Philippe Deléham, Aug 29 2006
a(n) is the number of binary relations on a set with n elements that are total relations, i.e., for a relation on a set X it holds for all a and b in X that a~b or b~a (or both). E.g., a(2) = 3 because there are three total relations on a set with two elements: {(a,a),(a,b),(b,a),(b,b)}, {(a,a),(a,b),(b,b)}, and {(a,a),(b,a),(b,b)}. - Geoffrey Critzer, May 23 2008
The number of semicomplete digraphs (or weak tournaments) on n labeled nodes. - Rémy-Robert Joseph, Nov 12 2012
The number of n X n binary matrices A that have a(i,j)=0 whenever a(j,i)=1 for i!=j and zeros on the diagonal. We need only consider the (n^2-n)/2 non-diagonal entry pairs . Since each pair is of the form <0,0>, <0,1>, or <1,0>, a(n) = 3^((n^2-n)/2). - Dennis P. Walsh, Apr 03 2014
a(n) is the number of symmetric (-1,0,1)-matrices of dimension (n-1) X (n-1). - Eric W. Weisstein, Jan 03 2021

Examples

			The a(2)=3 binary 2 X 2 matrices are [0 0; 0 0], [0 1; 0 0], and [0 0; 1 0]. - _Dennis P. Walsh_, Apr 03 2014
		

References

  • P. A. MacMahon, Chess tournaments and the like treated by the calculus of symmetric functions, Coll. Papers I, MIT Press, 344-375.

Crossrefs

Cf. A007747.

Programs

Formula

a(n+1) is the determinant of an n X n matrix M_(i, j) = C(3*i,j). - Benoit Cloitre, Aug 27 2003
Sequence is given by the Hankel transform (see A001906 for definition) of A007564 = {1, 1, 4, 19, 100, 562, 3304, ...}; example: det([1, 1, 4, 19; 1, 4, 19, 100; 4, 19, 100, 562; 19, 100, 562, 3304]) = 3^6 = 729. - Philippe Deléham, Aug 20 2005
The sequence a(n+1) = [1,3,27,729,59049,14348907,...] is the Hankel transform (see A001906 for definition) of A047891 = 1, 3, 12, 57, 300, 1586, 9912, ... . - Philippe Deléham, Aug 29 2006
a(n) = 3^binomial(n,2). - Zerinvary Lajos, Jun 16 2007
G.f. A(x) satisfies: A(x) = 1 + x * A(3*x). - Ilya Gutkovskiy, Jun 04 2020
a(n) = a(n-1)*3^(n-1), a(0) = 1. - Mehdi Naima, Mar 09 2022

A053291 Nonsingular n X n matrices over GF(4).

Original entry on oeis.org

1, 3, 180, 181440, 2961100800, 775476766310400, 3251791214634074112000, 218210695042457748180566016000, 234298374547168764346587444978647040000, 4025200069765920285793155323595159699896401920000, 1106437515026051855463365435310419366987397763763798016000000
Offset: 0

Views

Author

Stephen G Penrice, Mar 04 2000

Keywords

Crossrefs

Programs

  • Magma
    [1] cat [&*[(4^n - 4^k): k in [0..n-1]]: n in [1..8]]; // Bruno Berselli, Jan 28 2013
    
  • Mathematica
    Table[Product[4^n - 4^k, {k,0,n-1}], {n,0,10}] (* Geoffrey Critzer, Jan 26 2013 *)
  • PARI
    for(n=0,10, print1(prod(k=0,n-1, 4^n - 4^k), ", ")) \\ G. C. Greubel, May 31 2018

Formula

a(n) = (4^n - 1)*(4^n - 4)*...*(4^n - 4^(n-1)).
a(n) = A053763(n)*A027637(n). - Bruno Berselli, Jan 30 2013
From Amiram Eldar, Jul 06 2025: (Start)
a(n) = Product_{k=1..n} A115490(k).
a(n) ~ c * 4^(n^2), where c = A100221. (End)

Extensions

More terms from Vladeta Jovovic, Mar 16 2000

A003787 Order of universal Chevalley group A_n (3).

Original entry on oeis.org

1, 24, 5616, 12130560, 237783237120, 42064805779476480, 67034222101339041669120, 961721214905722855895197286400, 124190524600592082795473760093457612800, 144339416867688029764487130056208182629053235200
Offset: 0

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Author

Keywords

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], p. xvi.
  • H. S. M. Coxeter and W. O. J. Moser, Generators and Relations for Discrete Groups, 4th ed., Springer-Verlag, NY, reprinted 1984, p. 131.

Crossrefs

Programs

  • Magma
    [&*[(3^n - 3^k): k in [0..n-1]]/2: n in [1..10]]; // Vincenzo Librandi, Sep 19 2015
  • Mathematica
    f[m_, n_] := m^(n (n + 1)/2) Product[m^k - 1, {k, 2, n + 1}];
    f[3, #] & /@ Range[0, 9] (* Michael De Vlieger, Sep 18 2015 *)

Formula

Numbers so far appear to equal A053290(n)/2. - Ralf Stephan, Mar 30 2004
a(n) = A(3,n) where A(q,n) = q^(n*(n+1)/2) * Product_{k=2..n+1}(q^k-1). - Sean A. Irvine, Sep 18 2015
a(n) ~ c * 3^(n*(n+2)), where c = (3/2) * A100220 = 0.840189116891... . - Amiram Eldar, Jul 07 2025

Extensions

One more term from Sean A. Irvine, Sep 18 2015

A053292 Number of nonsingular n X n matrices over GF(5).

Original entry on oeis.org

1, 4, 480, 1488000, 116064000000, 226614960000000000, 11064475422000000000000000, 13506266841692625000000000000000000, 412177498341354683437500000000000000000000000
Offset: 0

Views

Author

Stephen G Penrice, Mar 04 2000

Keywords

Crossrefs

Programs

  • Magma
    [1] cat [&*[(5^n - 5^k): k in [0..n-1]]: n in [1..8]]; // Bruno Berselli, Jan 28 2013
    
  • Mathematica
    Table[Product[5^n - 5^k, {k,0,n-1}], {n,0,10}] (* Geoffrey Critzer, Jan 26 2013 *)
  • PARI
    for(n=0,10, print1(prod(k=0,n-1, 5^n - 5^k), ", ")) \\ G. C. Greubel, May 31 2018

Formula

a(n) = (5^n - 1)*(5^n - 5)*...*(5^n - 5^(n-1)).
a(n) = A109345(n)*A027872(n). - Bruno Berselli, Jan 30 2013
a(n) ~ c * 5^(n^2), where c = A100222. - Amiram Eldar, Jul 06 2025

Extensions

More terms from Vladeta Jovovic, Mar 16 2000

A053293 Number of nonsingular n X n matrices over GF(7).

Original entry on oeis.org

1, 6, 2016, 33784128, 27811094169600, 1122211189922928537600, 2218959336124989671614429593600, 214992513152176999576908105619651923148800, 1020690003311610463765638355505358381593396977336320000, 237443634207909205360438080389756681126654524500073656592021585920000
Offset: 0

Views

Author

Stephen G Penrice, Mar 04 2000

Keywords

Crossrefs

Programs

  • Magma
    [1] cat [&*[(7^n - 7^k): k in [0..n-1]]: n in [1..7]]; // Bruno Berselli, Jan 28 2013
    
  • Mathematica
    Table[Product[7^n - 7^k, {k, 0, n-1}], {n, 0, 10}] (* Vincenzo Librandi, Jan 28 2013 *)
  • PARI
    for(n=0,10, print1(prod(k=0,n-1, 7^n - 7^k), ", ")) \\ G. C. Greubel, May 31 2018

Formula

a(n) = (7^n - 1)*(7^n - 7)*...*(7^n - 7^(n-1)).
a(n) = A109493(n)*A027875(n). - Bruno Berselli, Jan 30 2013
a(n) ~ c * 7^(n^2), where c = A132035. - Amiram Eldar, Jul 06 2025

Extensions

More terms from Vladeta Jovovic, Mar 16 2000

A060722 a(n) = 3^(n^2).

Original entry on oeis.org

1, 3, 81, 19683, 43046721, 847288609443, 150094635296999121, 239299329230617529590083, 3433683820292512484657849089281, 443426488243037769948249630619149892803
Offset: 0

Views

Author

Avi Peretz (njk(AT)netvision.net.il), Apr 21 2001

Keywords

Comments

The number of n X n {-1,0,1}-matrices (the same as the number of n X n matrices over GF(3) ).

Crossrefs

Programs

  • Maple
    for n from 1 to 15 do printf(`%d,`,3^(n^2)) od:
  • Mathematica
    Array[3^(#^2) &, 9] (* Michael De Vlieger, Jul 12 2018 *)
  • PARI
    { for (n=0, 45, write("b060722.txt", n, " ", 3^(n^2)); ) } \\ Harry J. Smith, Jul 10 2009
    
  • PARI
    a(n) = 3^(n^2); \\ Joerg Arndt, Feb 23 2014

Formula

a(n) = [x^n] 1/(1 - 3^n*x). - Ilya Gutkovskiy, Oct 10 2017
From Geoffrey Critzer, Dec 02 2024: (Start)
a(n) = Sum_{k=0..n} A378666(n,k)*A053764(k)*A053290(n-k).
Sum_{n>=0} a(n)x^n/B(n) = f(x)*g(x) where f(x) = Sum_{n>=0} A053290(n)x^n/B(n) and g(x) = Sum_{n>=0} A053764(n)x^n/B(n) and B(n) = A053290(n)/2^n. (End)

Extensions

More terms from James Sellers, Apr 24 2001
a(0) = 1 added by N. J. A. Sloane, Nov 23 2007

A015001 q-factorial numbers for q=3.

Original entry on oeis.org

1, 1, 4, 52, 2080, 251680, 91611520, 100131391360, 328430963660800, 3232089113385932800, 95424198983606279987200, 8452007576574959037306265600, 2245867453247498115393020895232000, 1790317944898228845164815929864036352000
Offset: 0

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Author

Keywords

Comments

a(n) is the number of maximal chains in the lattice of subspaces of an n-dimensional vector space over GF(3). - Geoffrey Critzer, Sep 07 2022

Crossrefs

Programs

  • Magma
    [n le 1 select 1 else (3^n-1)*Self(n-1)/2: n in [1..15]]; // Vincenzo Librandi, Oct 22 2012
  • Mathematica
    RecurrenceTable[{a[1]==1, a[n]==((3^n - 1) * a[n-1])/2}, a, {n,15}] (* Vincenzo Librandi, Oct 27 2012 *)
    Table[QFactorial[n, 3], {n, 15}] (* Bruno Berselli, Aug 14 2013 *)

Formula

a(n) = Product_{k=1..n} (q^k - 1) / (q - 1).
a(0) = 1, a(n) = (3^n - 1)*a(n-1)/2. - Vincenzo Librandi, Oct 27 2012
a(n) = (Product_{i=0..n-1} (q^n-q^i))/((q-1)^n*q^binomial(n,2)) = A053290(n)/(A000079(n)*A047656(n)). - Geoffrey Critzer, Sep 07 2022
From Amiram Eldar, Jul 05 2025: (Start)
a(n) = Product_{k=1..n} A003462(k).
a(n) ~ c * 3^(n*(n+1)/2)/2^n, where c = A100220. (End)

Extensions

a(0)=1 prepended by Alois P. Heinz, Sep 08 2021

A316622 Array read by antidiagonals: T(n,k) is the order of the group GL(n,Z_k).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 2, 6, 1, 1, 2, 48, 168, 1, 1, 4, 96, 11232, 20160, 1, 1, 2, 480, 86016, 24261120, 9999360, 1, 1, 6, 288, 1488000, 1321205760, 475566474240, 20158709760, 1, 1, 4, 2016, 1886976, 116064000000, 335522845163520, 84129611558952960, 163849992929280, 1
Offset: 0

Views

Author

Andrew Howroyd, Jul 08 2018

Keywords

Comments

All rows are multiplicative.
Equivalently, the number of invertible n X n matrices mod k.
Also, for k prime (but not higher prime powers) the number of nonsingular n X n matrices over GF(k).
For k >= 2, n! divides T(n,k) since the subgroup of GL(n,k) consisting of all permutation matrices is isomorphic to S_n (the n-th symmetric group). Note that a permutation matrix is an orthogonal matrix, hence having determinant +-1. - Jianing Song, Oct 29 2022

Examples

			Array begins:
=================================================================
n\k| 1       2         3          4             5           6
---+-------------------------------------------------------------
0  | 1       1         1          1            1            1 ...
1  | 1       1         2          2            4            2 ...
2  | 1       6        48         96          480          288 ...
3  | 1     168     11232      86016      1488000      1886976 ...
4  | 1   20160  24261120 1321205760 116064000000 489104179200 ...
5  | 1 9999360  ...
...
		

Crossrefs

Rows n=2..4 are A000252, A064767, A305186.
Columns k=2..7 are A002884, A053290, A065128, A053292, A065498, A053293.
Cf. A053291 (GF(4)), A052496 (GF(8)), A052497 (GF(9)).
Cf. A316623.

Programs

  • GAP
    T:=function(n,k) if k=1 or n=0 then return 1; else return Order(GL(n, Integers mod k)); fi; end;
    for n in [0..5] do Print(List([1..6], k->T(n,k)), "\n"); od;
    
  • Mathematica
    T[, 1] = T[0, ] = 1; T[n_, k_] := T[n, k] = Module[{f = FactorInteger[k], p, e}, If[Length[f] == 1, {p, e} = f[[1]]; (p^e)^(n^2)* Product[(1 - 1/p^j), {j, 1, n}], Times @@ (T[n, Power @@ #]& /@ f)]];
    Table[T[n - k + 1, k], {n, 0, 8}, {k, n + 1, 1, -1}] // Flatten (* Jean-François Alcover, Jul 25 2019 *)
  • PARI
    T(n,k)={my(f=factor(k)); k^(n^2) * prod(i=1, #f~, my(p=f[i,1]); prod(j=1, n, (1 - p^(-j))))}

Formula

T(n,p^e) = (p^e)^(n^2) * Product_{j=1..n} (1 - 1/p^j) for prime p.

A053846 Number of n X n matrices over GF(3) of order dividing 2 (i.e., number of solutions of X^2=I in GL(n,3)).

Original entry on oeis.org

1, 2, 14, 236, 12692, 1783784, 811523288, 995733306992, 3988947598331024, 43581058503809001248, 1559669026899267564563936, 152805492791495918971070907584, 49094725258525117931062810300451648, 43237014297639482582550110281347475757696, 124920254287369111633119733942816364074145497472
Offset: 0

Views

Author

Vladeta Jovovic, Mar 28 2000

Keywords

Comments

Or, number of n X n invertible diagonalizable matrices over GF(3).

Examples

			a(2) = 14 because we have: {{0, 1}, {1, 0}}, {{0, 2}, {2, 0}}, {{1, 0}, {0, 1}}, {{1, 0}, {0,2}}, {{1, 0}, {1, 2}}, {{1, 0}, {2, 2}}, {{1, 1}, {0, 2}}, {{1,2}, {0, 2}}, {{2, 0}, {0, 1}}, {{2, 0}, {0, 2}}, {{2, 0}, {1,1}}, {{2, 0}, {2, 1}}, {{2, 1}, {0, 1}}, {{2, 2}, {0, 1}}. - _Geoffrey Critzer_, Aug 05 2017
		

References

  • Vladeta Jovovic, The cycle index polynomials of some classical groups, Belgrade, 1995, unpublished.

Crossrefs

Row sums of A378666.

Programs

  • Maple
    T:= proc(n, k) option remember; `if`(k<0 or k>n, 0,
          `if`(n=0, 1, T(n-1, k-1)+3^k*T(n-1, k)))
        end:
    a:= n-> add(3^(k*(n-k))*T(n, k), k=0...n):
    seq(a(n), n=0..15);  # Alois P. Heinz, Aug 06 2017
  • Mathematica
    nn = 14; g[ n_] := (q - 1)^n q^Binomial[n, 2] FunctionExpand[
    QFactorial[n, q]] /. q -> 3; G[z_] := Sum[z^k/g[k], {k, 0, nn}];Table[g[n], {n, 0, nn}] CoefficientList[Series[G[z]^2, {z, 0, nn}], z] (* Geoffrey Critzer, Aug 05 2017 *)
  • PARI
    a(n)={my(v=[1]); for(n=1,n,v=vector(#v+1,k,if(k>1, v[k-1]) + if(k<=#v, 3^(k-1)*v[k]))); sum(k=0,n,3^(k*(n-k))*v[k+1])} \\ Andrew Howroyd, Mar 02 2018
    
  • Python
    from sympy.core.cache import cacheit
    @cacheit
    def T(n, k): return 0 if k<0 or k>n else 1 if n==0 else T(n - 1, k - 1) + 3**k*T(n - 1, k)
    def a(n): return sum(3**(k*(n - k))*T(n, k) for k in range(n + 1))
    print([a(n) for n in range(15)]) # Indranil Ghosh, Aug 06 2017, after Maple code

Formula

a(n)/A053290(n) is the coefficient of x^n in (Sum_{n>=0} x^n/A053290(n))^2. - Geoffrey Critzer, Aug 05 2017

Extensions

More terms from Geoffrey Critzer, Aug 05 2017

A052496 Number of nonsingular n X n matrices over GF(8).

Original entry on oeis.org

1, 7, 3528, 115379712, 241909719367680, 32467582052437076213760, 278893342293098904613804037898240, 153323163270070838469523866093442017326530560
Offset: 0

Views

Author

Vladeta Jovovic, Mar 16 2000

Keywords

Crossrefs

Programs

  • Magma
    [1] cat [&*[(8^n-8^k): k in [0..n-1]]: n in [1..10]]; // Bruno Berselli, Jan 30 2013
    
  • Mathematica
    Table[Product[(8^n - 8^j), {j, 0, n-1}], {n, 0, 10}] (* G. C. Greubel, May 14 2019 *)
  • PARI
    {a(n) = prod(j=0,n-1, 8^n - 8^j)}; \\ G. C. Greubel, May 14 2019
    
  • Sage
    [product(8^n - 8^j for j in (0..n-1)) for n in (0..10)] # G. C. Greubel, May 14 2019

Formula

a(n) = (8^n - 1)*(8^n - 8)*...*(8^n - 8^(n-1)).
a(n) = A109966(n)*A027876(n). - Bruno Berselli, Jan 30 2013
a(n) ~ c * 8^(n^2), where c = A132036. - Amiram Eldar, Jul 06 2025
Showing 1-10 of 31 results. Next