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.

Previous Showing 11-18 of 18 results.

A055084 Number of 6 X n binary matrices with no zero rows or columns, up to row and column permutation.

Original entry on oeis.org

1, 15, 180, 2001, 20755, 200082, 1781941, 14637962, 111011667, 779695050, 5093379110, 31092553357, 178203364143, 963217652830, 4930357535218, 23989343505296, 111335037107474, 494383391324356, 2106346854756098
Offset: 1

Views

Author

Vladeta Jovovic, Jun 13 2000

Keywords

Crossrefs

Column k=6 of A056152.

Programs

A321615 Triangle read by rows: T(n,k) is the number of k X k integer matrices with sum of elements n, with no zero rows or columns, up to row and column permutation.

Original entry on oeis.org

1, 0, 1, 0, 1, 1, 0, 1, 2, 1, 0, 1, 6, 3, 1, 0, 1, 9, 13, 3, 1, 0, 1, 17, 38, 20, 3, 1, 0, 1, 23, 97, 82, 23, 3, 1, 0, 1, 36, 217, 311, 126, 24, 3, 1, 0, 1, 46, 453, 968, 624, 151, 24, 3, 1, 0, 1, 65, 868, 2825, 2637, 933, 162, 24, 3, 1, 0, 1, 80, 1585, 7394, 10098, 4942, 1132, 165, 24, 3, 1
Offset: 0

Views

Author

Andrew Howroyd, Nov 14 2018

Keywords

Comments

Also the number of non-isomorphic multiset partitions of weight n with k parts and k vertices, where the weight of a multiset partition is the sum of sizes of its parts. - Gus Wiseman, Nov 18 2018

Examples

			Triangle begins:
    1
    0  1
    0  1    1
    0  1    2    1
    0  1    6    3    1
    0  1    9   13    3    1
    0  1   17   38   20    3    1
    0  1   23   97   82   23    3    1
    0  1   36  217  311  126   24    3    1
    0  1   46  453  968  624  151   24    3    1
    0  1   65  868 2825 2637  933  162   24    3    1
		

Crossrefs

Programs

  • Mathematica
    (* See A318795 for M[m, n, k]. *)
    T[n_, k_] := M[k, k, n] - 2 M[k, k-1, n] + M[k-1, k-1, n];
    Table[T[n, k], {n, 1, 11}, {k, 1, n}] // Flatten (* Jean-François Alcover, Nov 24 2018, from PARI *)
  • PARI
    \\ See A318795 for M.
    T(n, k) = if(k==0, n==0, M(k, k, n) - 2*M(k, k-1, n) + M(k-1, k-1, n));
    
  • PARI
    \\ See A340652 for G.
    T(n)={[Vecrev(p) | p<-Vec(1 + sum(k=1, n, y^k*(polcoef(G(k, n, n, y), k, y) - polcoef(G(k-1, n, n, y), k, y))))]}
    { my(A=T(10)); for(i=1, #A, print(A[i])) } \\ Andrew Howroyd, Jan 16 2024

Extensions

Column k=0 inserted by Andrew Howroyd, Jan 17 2024

A055082 Number of 4 X n binary matrices with no zero rows or columns, up to row and column permutation.

Original entry on oeis.org

1, 8, 42, 179, 633, 2001, 5745, 15274, 38000, 89331, 199715, 427184, 878152, 1741964, 3345562, 6239390, 11327863, 20065972, 34747460, 58924066, 98002370, 160086580, 257148244, 406637336, 633669040, 973971441, 1477810227, 2215179768, 3282598034, 4811946882
Offset: 1

Views

Author

Vladeta Jovovic, Jun 13 2000

Keywords

Crossrefs

Column k=4 of A056152.

Programs

Extensions

Terms a(21) and beyond from Andrew Howroyd, Mar 25 2020

A055083 Number of 5 X n binary matrices with no zero rows or columns, up to row and column permutation.

Original entry on oeis.org

1, 11, 91, 633, 3835, 20755, 102089, 461272, 1930310, 7534742, 27602968, 95428291, 312864361, 976985630, 2917175450, 8357692894, 23046527311, 61337188725, 157950527167, 394427897066, 957058104818, 2260601179661, 5206447640059, 11709619965923, 25752660738209
Offset: 1

Views

Author

Vladeta Jovovic, Jun 13 2000

Keywords

Crossrefs

Column k=5 of A056152.

Programs

Extensions

Terms a(21) and beyond from Andrew Howroyd, Mar 25 2020

A056037 Number of 6x6 binary matrices with n ones, with no zero rows or columns, up to row and column permutation.

Original entry on oeis.org

1, 2, 15, 69, 288, 840, 2144, 4488, 8317, 13160, 18636, 23078, 25856, 25623, 23187, 18713, 13932, 9288, 5816, 3256, 1767, 858, 419, 180, 88, 34, 16, 6, 3, 1, 1
Offset: 6

Views

Author

Vladeta Jovovic, Aug 04 2000

Keywords

Comments

Sum_{k=0..36} a(n)=A054976(6).

Crossrefs

Cf. A052370.

Formula

G.f. : Z(S_6 X S_6; x_1, x_2, ...)-2*Z(S_6 X S_5; x_1, x_2, ...)+Z(S_5 X S_5; x_1, x_2, ...) if we replace x_i by 1+x^i, where Z(S_i X S_j; x_1, x_2, ...) is cycle index of Cartesian product of symmetric groups S_i and S_j of degree i and j, respectively.

A056079 Number of 7 X 7 binary matrices with n ones, with no zero rows or columns, up to row and column permutation.

Original entry on oeis.org

1, 2, 15, 79, 420, 1744, 6197, 18715, 50042, 118121, 250025, 475791, 820987, 1287695, 1845875, 2423114, 2923474, 3246721, 3327677, 3150758, 2761802, 2242711, 1690526, 1183725, 771951, 469281, 267108, 142542, 71844, 34271, 15685, 6861, 2948, 1223, 513, 209, 90, 34, 16, 6, 3, 1, 1
Offset: 7

Views

Author

Vladeta Jovovic, Aug 04 2000

Keywords

Comments

Sum_{k=0..49} a(n)=A054976(7).

Crossrefs

Cf. A053304.

Formula

G.f. : Z(S_7 X S_7; x_1, x_2, ...)-2*Z(S_7 X S_6; x_1, x_2, ...)+Z(S_6 X S_6; x_1, x_2, ...) if we replace x_i by 1+x^i, where Z(S_i X S_j; x_1, x_2, ...) is cycle index of Cartesian product of symmetric groups S_i and S_j of degree i and j, respectively.

Extensions

More terms from Sean A. Irvine, Apr 14 2022

A056080 Number of 5 X 5 binary matrices with n ones, with no zero rows or columns, up to row and column permutation.

Original entry on oeis.org

1, 2, 14, 49, 131, 248, 410, 531, 601, 566, 474, 336, 222, 124, 67, 32, 16, 6, 3, 1, 1
Offset: 5

Views

Author

Vladeta Jovovic, Aug 04 2000

Keywords

Comments

Sum_{k=0..25} a(n)=A054976(5).

Crossrefs

Cf. A052371.

Formula

G.f. : Z(S_5 X S_5; x_1, x_2, ...)-2*Z(S_5 X S_4; x_1, x_2, ...)+Z(S_4 X S_4; x_1, x_2, ...) if we replace x_i by 1+x^i, where Z(S_i X S_j; x_1, x_2, ...) is cycle index of Cartesian product of symmetric groups S_i and S_j of degree i and j, respectively.

A321733 Number of (0,1)-matrices with n ones, no zero rows or columns, and the same row sums as column sums.

Original entry on oeis.org

1, 1, 2, 8, 40, 246, 1816, 15630, 153592, 1696760, 20816358, 280807868, 4131117440, 65823490088, 1129256780408
Offset: 0

Views

Author

Gus Wiseman, Nov 18 2018

Keywords

Examples

			The a(4) = 40 matrices:
  [1 1]
  [1 1]
.
  [1 1 0][1 1 0][1 0 1][1 0 1][1 0 0]
  [1 0 0][0 0 1][1 0 0][0 1 0][0 1 1]
  [0 0 1][1 0 0][0 1 0][1 0 0][0 1 0]
.
  [1 0 0][0 1 1][0 1 0][0 1 0][0 1 0]
  [0 0 1][1 0 0][1 1 0][1 0 1][0 1 1]
  [0 1 1][1 0 0][0 0 1][0 1 0][1 0 0]
.
  [0 1 0][0 0 1][0 0 1][0 0 1][0 0 1]
  [0 0 1][1 1 0][1 0 0][0 1 0][0 0 1]
  [1 0 1][0 1 0][0 1 1][1 0 1][1 1 0]
.
  [1 0 0 0][1 0 0 0][1 0 0 0][1 0 0 0][1 0 0 0][1 0 0 0]
  [0 1 0 0][0 1 0 0][0 0 1 0][0 0 1 0][0 0 0 1][0 0 0 1]
  [0 0 1 0][0 0 0 1][0 1 0 0][0 0 0 1][0 1 0 0][0 0 1 0]
  [0 0 0 1][0 0 1 0][0 0 0 1][0 1 0 0][0 0 1 0][0 1 0 0]
.
  [0 1 0 0][0 1 0 0][0 1 0 0][0 1 0 0][0 1 0 0][0 1 0 0]
  [1 0 0 0][1 0 0 0][0 0 1 0][0 0 1 0][0 0 0 1][0 0 0 1]
  [0 0 1 0][0 0 0 1][1 0 0 0][0 0 0 1][1 0 0 0][0 0 1 0]
  [0 0 0 1][0 0 1 0][0 0 0 1][1 0 0 0][0 0 1 0][1 0 0 0]
.
  [0 0 1 0][0 0 1 0][0 0 1 0][0 0 1 0][0 0 1 0][0 0 1 0]
  [1 0 0 0][1 0 0 0][0 1 0 0][0 1 0 0][0 0 0 1][0 0 0 1]
  [0 1 0 0][0 0 0 1][1 0 0 0][0 0 0 1][1 0 0 0][0 1 0 0]
  [0 0 0 1][0 1 0 0][0 0 0 1][1 0 0 0][0 1 0 0][1 0 0 0]
.
  [0 0 0 1][0 0 0 1][0 0 0 1][0 0 0 1][0 0 0 1][0 0 0 1]
  [1 0 0 0][1 0 0 0][0 1 0 0][0 1 0 0][0 0 1 0][0 0 1 0]
  [0 1 0 0][0 0 1 0][1 0 0 0][0 0 1 0][1 0 0 0][0 1 0 0]
  [0 0 1 0][0 1 0 0][0 0 1 0][1 0 0 0][0 1 0 0][1 0 0 0]
		

Crossrefs

Programs

  • Mathematica
    prs2mat[prs_]:=Table[Count[prs,{i,j}],{i,Union[First/@prs]},{j,Union[Last/@prs]}];
    multsubs[set_,k_]:=If[k==0,{{}},Join@@Table[Prepend[#,set[[i]]]&/@multsubs[Drop[set,i-1],k-1],{i,Length[set]}]];
    Table[Length[Select[Subsets[Tuples[Range[n],2],{n}],And[Union[First/@#]==Range[Max@@First/@#]==Union[Last/@#],Total/@prs2mat[#]==Total/@Transpose[prs2mat[#]]]&]],{n,5}]

Extensions

a(7)-a(14) from Lars Blomberg, May 23 2019
Previous Showing 11-18 of 18 results.