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 10 results.

A173760 Partials sums of A000410.

Original entry on oeis.org

0, 0, 6, 431, 66056, 27960727, 35744362616, 144901919316449
Offset: 1

Views

Author

Jonathan Vos Post, Feb 23 2010

Keywords

Comments

Partials sums of number of singular n X n rational (0,1)-matrices. The subsequence of primes in this partial sum begins: 431.

Examples

			a(8) = 0 + 0 + 6 + 425 + 65625 + 27894671 + 35716401889 + 144866174953833.
		

Crossrefs

Formula

a(n) = SUM[i=0..n] A000410(i).

A002884 Number of nonsingular n X n matrices over GF(2) (order of the group GL(n,2)); order of Chevalley group A_n (2); order of projective special linear group PSL_n(2).

Original entry on oeis.org

1, 1, 6, 168, 20160, 9999360, 20158709760, 163849992929280, 5348063769211699200, 699612310033197642547200, 366440137299948128422802227200, 768105432118265670534631586896281600, 6441762292785762141878919881400879415296000, 216123289355092695876117433338079655078664339456000
Offset: 0

Views

Author

Keywords

Comments

Also number of bases for GF(2^n) over GF(2).
Also (apparently) number of n X n matrices over GF(2) having permanent = 1. - Hugo Pfoertner, Nov 14 2003
The previous comment is true because over GF(2) permanents and determinants are the same. - Joerg Arndt, Mar 07 2008
The number of automorphisms of (Z_2)^n (the direct product of n copies of Z_2). - Peter Eastwood, Apr 06 2015
Note that n! divides a(n) since the subgroup of GL(n,2) consisting of all permutation matrices is isomorphic to S_n (the n-th symmetric group). - Jianing Song, Oct 29 2022
The number of boolean operations on n bits, or quantum operations on n qubits, that can be constructed using only CNOT (controlled NOT) gates. - David Radcliffe, Jul 06 2025

Examples

			PSL_2(2) is isomorphic to the symmetric group S_3 of order 6.
		

References

  • Roger W. Carter, Simple groups of Lie type. Pure and Applied Mathematics, Vol. 28, John Wiley & Sons, London-New York-Sydney, 1972. viii+331pp. MR0407163 (53 #10946). See page 2.
  • 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.
  • K. J. Horadam, Hadamard matrices and their applications. Princeton University Press, Princeton, NJ, 2007. xiv+263 pp. See p. 132.
  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Column k=2 of A316622 and A316623.
Cf. A006516, A048651, A203303. Row sums of A381854.

Programs

  • Magma
    [1] cat [(&*[2^n -2^k: k in [0..n-1]]): n in [1..15]]; // G. C. Greubel, Aug 31 2023
    
  • Maple
    # First program
    A002884:= n-> mul(2^n - 2^i, i=0..n-1);
    seq(A002884(n), n = 0..12);
    # Second program
    A002884:= n-> 2^(n*(n-1)/2) * mul( 2^i - 1, i=1..n);
    seq(A002884(n), n=0..12);
  • Mathematica
    Table[Product[2^n-2^i,{i,0,n-1}],{n,0,13}] (* Harvey P. Dale, Aug 07 2011 *)
    Table[2^(n*(n-1)/2) QPochhammer[2, 2, n] // Abs, {n, 0, 11}] (* Jean-François Alcover, Jul 15 2017 *)
  • PARI
    a(n)=prod(i=2,n,2^i-1)<Charles R Greathouse IV, Jan 13 2012
    
  • SageMath
    [product(2^n -2^j for j in range(n)) for n in range(16)] # G. C. Greubel, Aug 31 2023

Formula

a(n) = Product_{i=0..n-1} (2^n-2^i).
a(n) = 2^(n*(n-1)/2) * Product_{i=1..n} (2^i - 1).
a(n) = A203303(n+1)/A203303(n). - R. J. Mathar, Jan 06 2012
a(n) = (6*a(n-1)^2*a(n-3) - 8*a(n-1)*a(n-2)^2) / (a(n-2)*a(n-3)) for n > 2. - Seiichi Manyama, Oct 20 2016
a(n) ~ A048651 * 2^(n^2). - Vaclav Kotesovec, May 19 2020
a(n) = A006125(n) * A005329(n). - John Keith, Jun 30 2021
a(n) = Product_{k=1..n} A006516(k). - Amiram Eldar, Jul 06 2025

A046747 Number of n X n rational {0,1}-matrices of determinant 0.

Original entry on oeis.org

1, 10, 338, 42976, 21040112, 39882864736, 292604283435872, 8286284310367538176
Offset: 1

Views

Author

Günter M. Ziegler (ziegler(AT)math.tu-berlin.de)

Keywords

Examples

			a(2)=10: the matrix of all 0's, 4 matrices with 2 zeros in the same row or column, 4 matrices with 3 zeros and the all-1 matrix.
		

Crossrefs

Programs

  • Mathematica
    Sum[KroneckerDelta[Det[Array[Mod[Floor[k/(2^(n*(#1-1)+#2-1))],2]&,{n,n}]],0],{k,0,(2^(n^2))-1}] (* John M. Campbell, Jun 24 2011 *)
    Count[Det /@ Tuples[{0, 1}, {n, n}], 0] (* David Trimas, Sep 23 2024 *)
  • PARI
    A046747(n) = m=matrix(n,n); ct=0; for(x=0,2^(n*n)-1,a=binary(x+2^(n*n)); for(i=1,n, for(j=1,n,m[i,j]=a[n*i+j+1-n])); if(matdet(m)==0,ct=ct+1,); ); ct \\ Randall L Rathbun
    
  • PARI
    a(n)=sum(i=0,2^n^2-1,matdet(matrix(n,n,x,y,(i>>(n*x+y-n-1))%2))==0) \\ Charles R Greathouse IV, Feb 21 2015

Formula

a(n) = 2^(n^2) - n! * binomial(2^n -1, n) + n! * A000410(n).
a(n) + A055165(n) = 2^(n^2) = total number of n X n (0, 1) matrices.
The probability that a random n X n {0,1}-matrix is singular is conjectured to be asymptotic to C(n+1, 2)*(1/2)^(n-1). [Corrected by N. J. A. Sloane, Jan 02 2007]

Extensions

a(8) from Vladeta Jovovic, Mar 28 2006

A116532 Number of singular n X n rational {0,1}-matrices with no zero rows or columns and with all rows distinct, up to permutation of rows.

Original entry on oeis.org

0, 0, 3, 285, 50820, 23551920, 31898503077, 134251404794199
Offset: 1

Views

Author

Vladeta Jovovic, Apr 03 2006

Keywords

Crossrefs

Binary matrices with distinct rows and columns, various versions: A059202, A088309, A088310, A088616, A089673, A089674, A093466, A094000, A094223, A116532, A116539, A181230, A259763

Formula

a(n) = A054780(n) - A088389(n).

A000409 Singular n X n (0,1)-matrices: the number of n X n (0,1)-matrices having distinct, nonzero ordered rows, but having at least two equal columns or at least one zero column.

Original entry on oeis.org

0, 6, 350, 43260, 14591171, 14657461469, 46173502811223, 474928141312623525, 16489412944755088235117, 1985178211854071817861662307, 846428472480689964807653763864449, 1299141117072945982773752362381072143359, 7268140170419155675761326840423792818571154945, 149650282980396792665043455999899697765782372693740287
Offset: 2

Views

Author

Keywords

Comments

This is a lower bound for the set of all n X n (0,1)-matrices having distinct, nonzero ordered rows and determinant 0 (compare A000410).
Here ordered means that we take only one representative from the n! matrices obtained by all permutations of the distinct rows of an n X n matrix.
a(n) is also the number of sets of n distinct nonzero (0,1)-vectors in R^n that do not span R^n.

References

  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Programs

  • Magma
    [ -(&+[StirlingFirst(n+1,k+1)*Binomial(2^k-1,n): k in [0..n-1]]): n in [2..15]]; // G. C. Greubel, Jun 05 2020
    
  • Maple
    with(combinat): T := proc(n) -sum(stirling1(n+1,k+1)*binomial(2^k-1,n),k=0..n-1); end proc:
  • Mathematica
    a[n_] := -Sum[ StirlingS1[n+1, k+1]*Binomial[2^k-1, n], {k, 0, n-1}]; Table[a[n], {n, 2, 15}] (* Jean-François Alcover, Nov 21 2012, from formula *)
  • PARI
    a(n) = -sum(k=0, n-1, stirling(n+1, k+1, 1)*binomial(2^k-1, n)); \\ Michel Marcus, Jun 05 2020
    
  • Sage
    [sum((-1)^(n+k+1)*stirling_number1(n+1,k+1)*binomial(2^k-1,n) for k in (0..n-1)) for n in (2..15)] # G. C. Greubel, Jun 05 2020

Formula

a(n) = (-1)*Sum_{k=0..n-1} Stirling1(n+1, k+1)*binomial(2^k-1, n).
a(n) = binomial(2^n-1, n) - A094000(n). - Vladeta Jovovic, Nov 27 2005

Extensions

Edited by W. Edwin Clark, Nov 02 2003

A064230 Triangle T(n,k) = number of rational (0,1) matrices of rank k (n >= 0, 0 <= k <= n).

Original entry on oeis.org

1, 1, 1, 1, 9, 6, 1, 49, 288, 174, 1, 225, 6750, 36000, 22560, 1, 961, 118800, 3159750, 17760600, 12514320, 1, 3969, 1807806, 190071000, 5295204600, 34395777360, 28836612000, 1, 16129, 25316928, 9271660734, 1001080231200, 32307576315840
Offset: 0

Views

Author

N. J. A. Sloane, Sep 23 2001

Keywords

Comments

Rows add to 2^(n^2).
Komlos and later Kahn, Komlos and Szemeredi show that almost all such matrices are invertible.
Table 3 from M. Zivkovic, Classification of small (0,1) matrices (see link). - Vladeta Jovovic, Mar 28 2006

Examples

			Triangle T(n,k) begins:
  1;
  1,   1;
  1,   9,      6;
  1,  49,    288,     174;
  1, 225,   6750,   36000,    22560;
  1, 961, 118800, 3159750, 17760600, 12514320;
  ...
		

References

  • J. Kahn, J. Komlos and E. Szemeredi: On the probability that a random +-1 matrix is singular, J. AMS 8 (1995), 223-240.
  • J. Komlos, On the determinants of random matrices, Studia Sci. Math. Hungar., 3 (1968), 387-399.

Crossrefs

Main diagonal gives A055165.

Programs

  • PARI
    T=matrix(5,5); { for(n=0,4, mm=matrix(n,n); for(k=0,n,T[1+n,1+k]=0); forvec(x=vector(n*n,i,[0,1]), for(i=1,n, for(j=1,n,mm[i,j]=x[i+n*(j-1)])); T[1+n,1+matrank(mm)]++); for(k=0,n,print1(T[1+n,1+k], if(k
    				

Formula

Sum_{k=1..n} k * T(n,k) = A086875(n). - Alois P. Heinz, Jun 18 2022

Extensions

More terms and PARI code from Michael Somos, Sep 25 2001
6 more terms from Lambert Klasen (Lambert.Klasen(AT)gmx.net), Dec 17 2004
More terms from Vladeta Jovovic, Mar 28 2006

A064231 Triangle read by rows: T(n,k) = number of rational (+1,-1) matrices of rank k (n >= 1, 1 <= k <= n).

Original entry on oeis.org

2, 8, 8, 32, 288, 192, 128, 6272, 36864, 22272, 512, 115200, 3456000, 18432000, 11550720, 2048, 1968128, 243302400, 6471168000, 36373708800, 25629327360, 8192, 32514048, 14809546752, 1557061632000, 43378316083200, 281770208133120
Offset: 1

Views

Author

N. J. A. Sloane, Sep 23 2001

Keywords

Comments

Rows add to 2^(n^2) = A002416. - Jonathan Vos Post, Feb 27 2011
Komlos and later Kahn, Komlos and Szemeredi show that almost all such matrices are invertible.

Examples

			2; 8,8; 32,288,192; 128,6272,36864,22272; ...
		

References

  • J. Kahn, J. Komlos and E. Szemeredi: On the probability that a random +-1 matrix is singular, J. AMS 8 (1995), 223-240.
  • J. Komlos, On the determinants of random matrices, Studia Sci. Math. Hungar., 3 (1968), 387-399.

Crossrefs

Programs

  • PARI
    T=matrix(4,4); { for(n=1,4, mm=matrix(n,n); for(k=1,n, T[n,k]=0); forvec(x=vector(n*n,i,[0,1]), for(i=1,n, for(j=1,n,mm[i,j]=(-1)^x[i+n*(j-1)])); T[n,matrank(mm)]++); for(k=1,n,print1(T[n,k], if(k
    				

Extensions

More terms and PARI code from Michael Somos, Sep 25 2001
More terms from Vladeta Jovovic, Apr 02 2006
Offset changed to 1 by T. D. Noe, Mar 02 2011

A116506 Number of singular n X n rational {0,1}-matrices with no zero rows.

Original entry on oeis.org

0, 3, 169, 28065, 16114831, 33686890209, 262530190180063, 7717643584470877185
Offset: 1

Views

Author

Vladeta Jovovic, Apr 03 2006

Keywords

Crossrefs

Formula

a(n) = A055601(n) - A055165(n).

A116527 Number of singular n X n rational {0,1}-matrices with no zero rows or columns and with all rows distinct and all columns distinct, up to permutation of rows.

Original entry on oeis.org

0, 0, 0, 75, 22365, 13303500, 21058940420, 98692672142610
Offset: 1

Views

Author

Vladeta Jovovic, Apr 03 2006

Keywords

Crossrefs

Formula

a(n) = A094000(n) - A088389(n).
Conjecture: a(n) = A000410(n) - A000409(n-1) for n>1. - Jean-François Alcover, Jan 08 2020

A116507 Number of singular n X n rational {0,1}-matrices with no zero rows or columns.

Original entry on oeis.org

0, 1, 91, 18943, 12483601, 28530385447, 235529139302185, 7183142489571818623
Offset: 1

Views

Author

Vladeta Jovovic, Apr 03 2006

Keywords

Crossrefs

Formula

a(n) = A048291(n) - A055165(n).
Showing 1-10 of 10 results.