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 1-4 of 4 results.

A055165 Number of invertible n X n matrices with entries equal to 0 or 1.

Original entry on oeis.org

1, 1, 6, 174, 22560, 12514320, 28836612000, 270345669985440, 10160459763342013440
Offset: 0

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Author

Ulrich Hermisson (uhermiss(AT)server1.rz.uni-leipzig.de), Jun 18 2000

Keywords

Comments

All eigenvalues are nonzero.

Examples

			For n=2 the 6 matrices are {{{0, 1}, {1, 0}}, {{0, 1}, {1, 1}}, {{1, 0}, {0, 1}}, {{1, 0}, {1, 1}}, {{1, 1}, {0, 1}}, {{1, 1}, {1, 0}}}.
		

Crossrefs

Cf. A056990, A056989, A046747, A055165, A002416, A003024 (positive definite matrices).
A046747(n) + a(n) = 2^(n^2) = total number of n X n (0, 1) matrices = sequence A002416.
Main diagonal of A064230.

Programs

  • PARI
    a(n)=sum(t=0,2^n^2-1,!!matdet(matrix(n,n,i,j,(t>>(i*n+j-n-1))%2))) \\ Charles R Greathouse IV, Feb 09 2016
    
  • Python
    from itertools import product
    from sympy import Matrix
    def A055165(n): return sum(1 for s in product([0,1],repeat=n**2) if Matrix(n,n,s).det() != 0) # Chai Wah Wu, Sep 24 2021

Formula

For an asymptotic estimate see A046747. A002884 is a lower bound. A002416 is an upper bound.
a(n) = n! * A088389(n). - Gerald McGarvey, Oct 20 2007

Extensions

More terms from Miodrag Zivkovic (ezivkovm(AT)matf.bg.ac.rs), Feb 28 2006
Description improved by Jeffrey Shallit, Feb 17 2016
a(0)=1 prepended by Alois P. Heinz, Jun 18 2022

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

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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).

A000410 Number of singular n X n rational (0,1)-matrices.

Original entry on oeis.org

0, 0, 6, 425, 65625, 27894671, 35716401889, 144866174953833
Offset: 1

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Author

Keywords

Comments

Number of all n X n (0,1)-matrices having distinct, nonzero ordered rows and determinant 0 - compare A000409.
a(n) is the number of singular n X n rational {0,1}-matrices with no zero rows and with all rows distinct, up to permutation of rows and so a(n) = binomial(2^n-1,n) - A088389(n). Cf. A116506, A116507, A116527, A116532. - Vladeta Jovovic, Apr 03 2006

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

Formula

n! * a(n) = A046747(n) - 2^(n^2) + n! * binomial(2^n -1, n).

Extensions

n=7 term from Guenter M. Ziegler (ziegler(AT)math.TU-Berlin.DE)
a(8) from Vladeta Jovovic, Mar 28 2006

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
Showing 1-4 of 4 results.