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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A089673 a(n) = number of n X n (0,1) matrices A such that the 2n+2 vectors consisting of the rows and the columns of the matrix A, as well as the main diagonal and the main antidiagonal, are all distinct.

Original entry on oeis.org

0, 0, 0, 652, 1658784, 10726929248, 172790068546048
Offset: 1

Views

Author

Vladeta Jovovic, Jan 04 2004

Keywords

Crossrefs

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

Extensions

a(6)-a(7) from Bert Dobbelaere, May 05 2025

A089674 a(n) = number of n X n (0,1) matrices A such that the 2n+2 vectors consisting of the rows and the columns of the matrix A, as well as the main diagonal read in the upward direction and the main antidiagonal, are all distinct.

Original entry on oeis.org

0, 0, 0, 1692, 2329280, 13441654352, 190945826194432
Offset: 1

Views

Author

Vladeta Jovovic, Jan 04 2004

Keywords

Crossrefs

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

Extensions

a(6)-a(7) from Bert Dobbelaere, May 05 2025

A094223 Number of binary n X n matrices with all rows (columns) distinct, up to permutation of columns (rows).

Original entry on oeis.org

1, 2, 7, 68, 2251, 247016, 89254228, 108168781424, 451141297789858, 6625037125817801312, 348562672319990399962384, 66545827618461283102105245248, 46543235997095840080425299916917968, 120155975713532210671953821005746669185792, 1152009540439950050422144845158703009569109376384
Offset: 0

Views

Author

Goran Kilibarda and Vladeta Jovovic, May 28 2004

Keywords

Crossrefs

Main diagonal of A059584 and A059587, A060690, A088309.
Binary matrices with distinct rows and columns, various versions: A059202, A088309, A088310, A088616, A089673, A089674, A093466, A094000, A094223, A116532, A116539, A181230, A259763

Programs

  • Mathematica
    a[n_] := Sum[(-1)^(n - k)*StirlingS1[n, k]*Binomial[2^k, n], {k, 0, n}]; (* or *) a[n_] := Sum[ StirlingS1[n, k]*Binomial[2^k + n - 1, n], {k, 0, n}]; Table[ a[n], {n, 0, 12}] (* Robert G. Wilson v, May 29 2004 *)
  • PARI
    a(n) = sum(k=0, n, stirling(n, k, 1)*binomial(2^k+n-1, n)); \\ Michel Marcus, Dec 17 2022

Formula

a(n) = Sum_{k=0..n} (-1)^(n-k)*Stirling1(n, k)*binomial(2^k, n).
a(n) = Sum_{k=0..n} Stirling1(n, k)*binomial(2^k+n-1, n).

Extensions

More terms from Robert G. Wilson v, May 29 2004
a(13) onwards from Andrew Howroyd, Jan 20 2024

A059203 Number of n-block T_0-covers of a labeled set.

Original entry on oeis.org

1, 1, 6, 2270, 148109472315, 186266607433353989829111737621541, 7485122439882901107741903784218892557452456923078744798141861944074340339271507786827
Offset: 0

Views

Author

Vladeta Jovovic, Goran Kilibarda, Jan 18 2001

Keywords

Comments

A cover of a set is a T_0-cover if for every two distinct points of the set there exists a member (block) of the cover containing one but not the other point.

Examples

			a(4) = 1 + (1/4!)*( - 50*[1!*e] + 35*[3!*e] - 10*[7!*e] + [15!*e]) = 1 + (1/4!)*( - 50*2 + 35*16 - 10*13700 + 3554627472076) = 148109472315, where [k!*e] := floor(k!*exp(1)).
		

Crossrefs

Cf. A059201, column sums of A059202, A059084 - A059089, A000522.

Programs

  • Maple
    with(combinat): Digits := 1500: f := n->(-1)^n+(1/n!)*sum(stirling1(n+1,i)*floor((2^(i-1)-1)!*exp(1)), i=2..n+1): for n from 1 to 10 do printf(`%d,`,f(n)) od:
  • Mathematica
    a[0] := 1; a[n_] := (-1)^n + (1/n!)*Sum[StirlingS1[n + 1, k]*Floor[(2^(k - 1) - 1)!*E], {k, 2, n + 1}]; Table[a[n], {n, 0, 5}] (* G. C. Greubel, Dec 28 2016 *)

Formula

a(n) = (- 1)^n + (1/n!)*Sum_{i = 2,..,n + 1} stirling1(n + 1, i)*floor((2^(i - 1) - 1)!*exp(1)), n>0, a(0) = 1.
a(n) = (1/n!)*Sum_{i = 1,..,n + 1} stirling1(n + 1, i)*A000522(2^(i - 1) - 1).

Extensions

More terms from James Sellers, Jan 24 2001

A318537 Irregular triangle read by rows: T(n,m) is the number of n X m (0,1)-matrices with pairwise distinct nonzero columns and pairwise distinct nonzero rows, n >= 0, m = 0..2^n-1.

Original entry on oeis.org

1, 0, 1, 0, 0, 6, 6, 0, 0, 6, 174, 840, 2520, 5040, 5040, 0, 0, 0, 840, 24360, 335160, 3553200, 32382000, 259459200, 1816214400, 10897286400, 54486432000, 217945728000, 653837184000, 1307674368000, 1307674368000, 0, 0, 0, 2520, 335160, 15198120, 476496720, 12767000400, 314181504000, 7288444800000
Offset: 0

Views

Author

Max Alekseyev, Aug 28 2018

Keywords

Comments

T(n,m) is divisible by both n! and m!, but not necessarily by n!*m!.
By symmetry T(n,m) = T(m,n).
T(n,2^n-1) = T(n,2^n-2) = (2^n-1)! = A028366(n).

Examples

			Triangle begins:
n=0: 1;
n=1: 0, 1;
n=2: 0, 0, 6, 6;
n=3: 0, 0, 6, 174, 840, 2520, 5040, 5040;
...
		

Crossrefs

Cf. A318538 (main diagonal), A059202.

Programs

  • PARI
    { A318537(n,m) = m! * sum(i=0,n, stirling(n+1,i+1)*binomial(2^i - 1,m)); }

Formula

T(n,m) = m! * Sum_{i=0..n} Stirling1(n+1,i+1) * binomial(2^i-1,m) = n! * Sum_{j=0..m} Stirling1(m+1,j+1) * binomial(2^j-1,n).
T(n,m) = A059202(n,m) * m!.

A318538 Number of n X n (0,1)-matrices with nonzero pairwise distinct rows and nonzero pairwise distinct columns.

Original entry on oeis.org

1, 1, 6, 174, 24360, 15198120, 38415132000, 376482729702240, 14139748304132048640, 2040859528996474439366400, 1141301651605590355550899891200, 2494751188402618305982805631973248000, 21474225685319103561274021904272069843353600
Offset: 0

Views

Author

Max Alekseyev, Aug 28 2018

Keywords

Crossrefs

Main diagonal of A318537.

Programs

  • PARI
    { A318538(n) = n! * sum(i=0, n, stirling(n+1, i+1) * binomial(2^i - 1, n) ); }

Formula

a(n) = n! * Sum_{i=0..n} Stirling1(n+1,i+1) * binomial(2^i-1,n).
a(n) = A318537(n,n).
a(n) = A094000(n) * n!.
Previous Showing 11-16 of 16 results.