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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A319766 Number of non-isomorphic strict intersecting multiset partitions (sets of multisets) of weight n whose dual is also a strict intersecting multiset partition.

Original entry on oeis.org

1, 1, 1, 4, 6, 14, 31, 64, 145, 324, 753
Offset: 0

Views

Author

Gus Wiseman, Sep 27 2018

Keywords

Comments

The dual of a multiset partition has, for each vertex, one part consisting of the indices (or positions) of the parts containing that vertex, counted with multiplicity. For example, the dual of {{1,2},{2,2}} is {{1},{1,2,2}}.
A multiset partition is intersecting iff no two parts are disjoint. The dual of a multiset partition is intersecting iff every pair of distinct vertices appear together in some part.
The weight of a multiset partition is the sum of sizes of its parts. Weight is generally not the same as number of vertices.

Examples

			Non-isomorphic representatives of the a(1) = 1 through a(5) = 14 multiset partitions:
1: {{1}}
2: {{1,1}}
3: {{1,1,1}}
   {{1,2,2}}
   {{1},{1,1}}
   {{2},{1,2}}
4: {{1,1,1,1}}
   {{1,2,2,2}}
   {{1},{1,1,1}}
   {{1},{1,2,2}}
   {{2},{1,2,2}}
   {{1,2},{2,2}}
5: {{1,1,1,1,1}}
   {{1,1,2,2,2}}
   {{1,2,2,2,2}}
   {{1},{1,1,1,1}}
   {{1},{1,2,2,2}}
   {{2},{1,1,2,2}}
   {{2},{1,2,2,2}}
   {{2},{1,2,3,3}}
   {{1,1},{1,1,1}}
   {{1,1},{1,2,2}}
   {{1,2},{1,2,2}}
   {{1,2},{2,2,2}}
   {{2,2},{1,2,2}}
   {{2},{1,2},{2,2}}
		

Crossrefs

A319768 Number of non-isomorphic strict multiset partitions (sets of multisets) of weight n whose dual is a (not necessarily strict) intersecting multiset partition.

Original entry on oeis.org

1, 1, 2, 5, 11, 25, 63, 144, 364, 905, 2356
Offset: 0

Views

Author

Gus Wiseman, Sep 27 2018

Keywords

Comments

The dual of a multiset partition has, for each vertex, one part consisting of the indices (or positions) of the parts containing that vertex, counted with multiplicity. For example, the dual of {{1,2},{2,2}} is {{1},{1,2,2}}.
The weight of a multiset partition is the sum of sizes of its parts. Weight is generally not the same as number of vertices.
A multiset partition is intersecting iff no two parts are disjoint. The dual of a multiset partition is intersecting iff every pair of distinct vertices appear together in some part.

Examples

			Non-isomorphic representatives of the a(1) = 1 through a(4) = 11 multiset partitions:
1: {{1}}
2: {{1,1}}
   {{1,2}}
3: {{1,1,1}}
   {{1,2,2}}
   {{1,2,3}}
   {{1},{1,1}}
   {{2},{1,2}}
4: {{1,1,1,1}}
   {{1,1,2,2}}
   {{1,2,2,2}}
   {{1,2,3,3}}
   {{1,2,3,4}}
   {{1},{1,1,1}}
   {{1},{1,2,2}}
   {{2},{1,2,2}}
   {{3},{1,2,3}}
   {{1,2},{2,2}}
   {{1},{2},{1,2}}
		

Crossrefs

A319769 Number of non-isomorphic intersecting set multipartitions (multisets of sets) of weight n whose dual is also an intersecting set multipartition.

Original entry on oeis.org

1, 1, 2, 3, 5, 7, 12, 16, 26, 38, 61
Offset: 0

Views

Author

Gus Wiseman, Sep 27 2018

Keywords

Comments

The dual of a multiset partition has, for each vertex, one part consisting of the indices (or positions) of the parts containing that vertex, counted with multiplicity. For example, the dual of {{1,2},{2,2}} is {{1},{1,2,2}}.
The weight of a multiset partition is the sum of sizes of its parts. Weight is generally not the same as number of vertices.
A multiset partition is intersecting iff no two parts are disjoint. The dual of a multiset partition is intersecting iff every pair of distinct vertices appear together in some part.

Examples

			Non-isomorphic representatives of the a(1) = 1 through a(5) = 7 set multipartitions:
1: {{1}}
2: {{1,2}}
   {{1},{1}}
3: {{1,2,3}}
   {{2},{1,2}}
   {{1},{1},{1}}
4: {{1,2,3,4}}
   {{3},{1,2,3}}
   {{1,2},{1,2}}
   {{2},{2},{1,2}}
   {{1},{1},{1},{1}}
5: {{1,2,3,4,5}}
   {{4},{1,2,3,4}}
   {{2,3},{1,2,3}}
   {{2},{1,2},{1,2}}
   {{3},{3},{1,2,3}}
   {{2},{2},{2},{1,2}}
   {{1},{1},{1},{1},{1}}
		

Crossrefs

A319773 Number of non-isomorphic intersecting set systems of weight n whose dual is also an intersecting set system.

Original entry on oeis.org

1, 1, 0, 1, 0, 0, 2, 1, 2, 4, 5
Offset: 0

Views

Author

Gus Wiseman, Sep 27 2018

Keywords

Comments

The dual of a multiset partition has, for each vertex, one part consisting of the indices (or positions) of the parts containing that vertex, counted with multiplicity. For example, the dual of {{1,2},{2,2}} is {{1},{1,2,2}}.
The weight of a multiset partition is the sum of sizes of its parts. Weight is generally not the same as number of vertices.
A multiset partition is intersecting iff no two parts are disjoint. The dual of a multiset partition is intersecting iff every pair of distinct vertices appear together in some part.

Examples

			Non-isomorphic representatives of the a(1) = 1 through a(10) = 5 set systems:
1:  {{1}}
3:  {{2},{1,2}}
6:  {{3},{2,3},{1,2,3}}
    {{1,2},{1,3},{2,3}}
7:  {{1,3},{2,3},{1,2,3}}
8:  {{2,4},{3,4},{1,2,3,4}}
    {{3},{1,3},{2,3},{1,2,3}}
9:  {{1,2,4},{1,3,4},{2,3,4}}
    {{4},{2,4},{3,4},{1,2,3,4}}
    {{1,2},{1,3},{1,4},{2,3,4}}
    {{1,2},{1,3},{2,3},{1,2,3}}
10: {{4},{3,4},{2,3,4},{1,2,3,4}}
    {{4},{1,2,4},{1,3,4},{2,3,4}}
    {{1,2},{2,4},{1,3,4},{2,3,4}}
    {{1,4},{2,4},{3,4},{1,2,3,4}}
    {{2,3},{2,4},{3,4},{1,2,3,4}}
		

Crossrefs

A321515 Number of nonnegative integer matrices with sum of entries equal to n, no zero rows or columns, and distinct rows and columns.

Original entry on oeis.org

1, 1, 3, 19, 137, 1209, 12899, 160395, 2276229, 36323217, 643848837, 12551081501, 266868756473, 6146455542737, 152439235077709, 4050427673024753, 114791270281213209, 3456412742412516649, 110191808168628510207, 3708004806262196242699, 131339701217968663631857
Offset: 0

Views

Author

Gus Wiseman, Nov 13 2018

Keywords

Examples

			The a(3) = 19 matrices:
  [3] [2 1] [1 2]
.
  [2] [2 0] [1 1] [1 1] [1] [1 0] [1 0] [0 2] [0 1] [0 1]
  [1] [0 1] [1 0] [0 1] [2] [1 1] [0 2] [1 0] [2 0] [1 1]
.
  [1 0 0] [1 0 0] [0 1 0] [0 1 0] [0 0 1] [0 0 1]
  [0 1 0] [0 0 1] [1 0 0] [0 0 1] [1 0 0] [0 1 0]
  [0 0 1] [0 1 0] [0 0 1] [1 0 0] [0 1 0] [1 0 0]
		

Crossrefs

Programs

  • Mathematica
    multsubs[set_,k_]:=If[k==0,{{}},Join@@Table[Prepend[#,set[[i]]]&/@multsubs[Drop[set,i-1],k-1],{i,Length[set]}]];
    prs2mat[prs_]:=Table[Count[prs,{i,j}],{i,Union[First/@prs]},{j,Union[Last/@prs]}];
    Table[Length[Select[multsubs[Tuples[Range[n],2],n],And[Union[First/@#]==Range[Max@@First/@#],Union[Last/@#]==Range[Max@@Last/@#],UnsameQ@@prs2mat[#],UnsameQ@@Transpose[prs2mat[#]]]&]],{n,5}]
  • PARI
    \\ Q(m,n,wf) defined in A321588.
    seq(n)={my(R=vectorv(n,m,Q(m,n,w->1/(1 - y^w) + O(y*y^n)))); for(i=2, #R, R[i] -= i*R[i-1]); Vec(1 + vecsum(vecsum(R)))} \\ Andrew Howroyd, Jan 24 2024

Extensions

a(7) onwards from Andrew Howroyd, Jan 20 2024

A321587 Number of (0,1)-matrices with n ones, no zero rows or columns, and distinct rows.

Original entry on oeis.org

1, 1, 3, 17, 129, 1227, 14123, 190265, 2934359, 50975647, 984801759, 20941104299, 486007744671, 12223797601887, 331190083773701, 9616356919931711, 297887922137531747, 9805965265937326129, 341827167387114704421, 12579123760272833723975, 487315396984696657840761
Offset: 0

Views

Author

Gus Wiseman, Nov 13 2018

Keywords

Comments

Also number of colored compositions of n using all colors of an initial interval of the color palette such that all parts have different color patterns and the patterns for parts i have i distinct colors in increasing order. a(3) = 17: 2ab1a, 2ab1b, 1a2ab, 1b2ab, 3abc, 2ab1c, 2ac1b, 2bc1a, 1a2bc, 1b2ac, 1c2ab, 1a1b1c, 1a1c1b, 1b1a1c, 1b1c1a, 1c1a1b, 1c1b1a. - Alois P. Heinz, Sep 17 2019

Examples

			The a(3) = 17 matrices:
  [1 1 1]
.
  [1 1] [1 1] [1 1 0] [1 0 1] [1 0] [1 0 0] [0 1 1] [0 1] [0 1 0] [0 0 1]
  [1 0] [0 1] [0 0 1] [0 1 0] [1 1] [0 1 1] [1 0 0] [1 1] [1 0 1] [1 1 0]
.
  [1 0 0] [1 0 0] [0 1 0] [0 1 0] [0 0 1] [0 0 1]
  [0 1 0] [0 0 1] [1 0 0] [0 0 1] [1 0 0] [0 1 0]
  [0 0 1] [0 1 0] [0 0 1] [1 0 0] [0 1 0] [1 0 0]
		

Crossrefs

Programs

  • Maple
    C:= binomial:
    b:= proc(n, i, k, p) option remember; `if`(n=0, p!, `if`(i<1, 0, add(
          b(n-i*j, min(n-i*j, i-1), k, p+j)*C(C(k, i), j), j=0..n/i)))
        end:
    a:= n-> add(add(b(n$2, i, 0)*(-1)^(k-i)*C(k, i), i=0..k), k=0..n):
    seq(a(n), n=0..21);  # Alois P. Heinz, Sep 16 2019
  • Mathematica
    prs2mat[prs_]:=Table[Count[prs,{i,j}],{i,Union[First/@prs]},{j,Union[Last/@prs]}];
    Table[Length[Select[Subsets[Tuples[Range[n],2],{n}],And[Union[First/@#]==Range[Max@@First/@#],Union[Last/@#]==Range[Max@@Last/@#],UnsameQ@@prs2mat[#]]&]],{n,5}]

Formula

a(n) ~ c * d^n * n!, where d = 1.938593839617140963759657977... and c = 0.350862127201784401195038... - Vaclav Kotesovec, Feb 05 2022

Extensions

a(7)-a(20) from Alois P. Heinz, Sep 16 2019

A316981 Number of non-isomorphic strict multiset partitions of weight n with no equivalent vertices.

Original entry on oeis.org

1, 1, 2, 6, 15, 40, 121
Offset: 0

Views

Author

Gus Wiseman, Jul 18 2018

Keywords

Comments

Also the number of nonnegative integer n X n matrices with sum of elements equal to n, under row and column permutations, with no equal rows and no equal columns.
In a multiset partition, two vertices are equivalent if in every block the multiplicity of the first is equal to the multiplicity of the second.

Examples

			Non-isomorphic representatives of the a(3) = 6 strict multiset partitions with no equivalent vertices (first column) and their duals (second column):
      (111) <-> (111)
      (122) <-> (1)(11)
    (1)(11) <-> (122)
    (1)(22) <-> (1)(22)
    (2)(12) <-> (2)(12)
  (1)(2)(3) <-> (1)(2)(3)
		

Crossrefs

A321401 Number of non-isomorphic strict self-dual multiset partitions of weight n.

Original entry on oeis.org

1, 1, 2, 4, 7, 14, 29, 57, 117, 240, 498
Offset: 0

Views

Author

Gus Wiseman, Nov 09 2018

Keywords

Comments

Also the number of nonnegative integer symmetric matrices up to row and column permutations with sum of elements equal to n and no zero rows or columns, in which the rows (or columns) are all different.
The dual of a multiset partition has, for each vertex, one part consisting of the indices (or positions) of the parts containing that vertex, counted with multiplicity. For example, the dual of {{1,2},{2,2}} is {{1},{1,2,2}}.

Examples

			Non-isomorphic representatives of the a(1) = 1 through a(5) = 14 multiset partitions:
  {{1}}  {{1,1}}    {{1,1,1}}      {{1,1,1,1}}        {{1,1,1,1,1}}
         {{1},{2}}  {{1},{2,2}}    {{1,1},{2,2}}      {{1,1},{1,2,2}}
                    {{2},{1,2}}    {{1},{2,2,2}}      {{1,1},{2,2,2}}
                    {{1},{2},{3}}  {{2},{1,2,2}}      {{1,2},{1,2,2}}
                                   {{1},{2},{3,3}}    {{1},{2,2,2,2}}
                                   {{1},{3},{2,3}}    {{2},{1,2,2,2}}
                                   {{1},{2},{3},{4}}  {{1},{2,2},{3,3}}
                                                      {{1},{2},{3,3,3}}
                                                      {{1},{3},{2,3,3}}
                                                      {{2},{1,2},{3,3}}
                                                      {{2},{1,3},{2,3}}
                                                      {{1},{2},{3},{4,4}}
                                                      {{1},{2},{4},{3,4}}
                                                      {{1},{2},{3},{4},{5}}
		

Crossrefs

A321406 Number of non-isomorphic self-dual set systems of weight n with no singletons.

Original entry on oeis.org

1, 0, 0, 0, 0, 0, 1, 1, 1, 2, 4
Offset: 0

Views

Author

Gus Wiseman, Nov 15 2018

Keywords

Comments

Also the number of 0-1 symmetric matrices up to row and column permutations with sum of elements equal to n and no zero rows or columns, in which the rows are all different and none sums to 1.
The dual of a multiset partition has, for each vertex, one part consisting of the indices (or positions) of the parts containing that vertex, counted with multiplicity. For example, the dual of {{1,2},{2,2}} is {{1},{1,2,2}}.
The weight of a multiset partition is the sum of sizes of its parts. Weight is generally not the same as number of vertices.

Examples

			Non-isomorphic representatives of the a(6) = 1 through a(10) = 4 set systems:
   6: {{1,2},{1,3},{2,3}}
   7: {{1,3},{2,3},{1,2,3}}
   8: {{1,2},{1,3},{2,4},{3,4}}
   9: {{1,2},{1,3},{1,4},{2,3,4}}
   9: {{1,2},{1,4},{3,4},{2,3,4}}
  10: {{1,2},{2,4},{1,3,4},{2,3,4}}
  10: {{1,3},{2,4},{1,3,4},{2,3,4}}
  10: {{1,4},{2,4},{3,4},{1,2,3,4}}
  10: {{1,2},{1,3},{2,4},{3,5},{4,5}}
		

Crossrefs

A321586 Number of nonnegative integer matrices with sum of entries equal to n, no zero rows or columns, and distinct rows (or distinct columns).

Original entry on oeis.org

1, 1, 4, 26, 204, 1992, 23336, 318080, 4948552, 86550424, 1681106080, 35904872576, 836339613984, 21100105791936, 573194015723840, 16681174764033728, 517768654898701120, 17074080118403865856, 596117945858272441408, 21967609729338776864384, 852095613819396775627200
Offset: 0

Views

Author

Gus Wiseman, Nov 13 2018

Keywords

Examples

			The a(3) = 26 matrices:
  [3][21][12][111]
.
  [2][20][11][11][110][101][1][10][10][100][02][011][01][01][010][001]
  [1][01][10][01][001][010][2][11][02][011][10][100][20][11][101][110]
.
  [100][100][010][010][001][001]
  [010][001][100][001][100][010]
  [001][010][001][100][010][100]
		

Crossrefs

Programs

  • Maple
    C:= binomial:
    b:= proc(n, i, k, p) option remember; `if`(n=0, p!, `if`(i<1, 0, add(
          b(n-i*j, min(n-i*j, i-1), k, p+j)*C(C(k+i-1, i), j), j=0..n/i)))
        end:
    a:= n-> add(add(b(n$2, i, 0)*(-1)^(k-i)*C(k, i), i=0..k), k=0..n):
    seq(a(n), n=0..21);  # Alois P. Heinz, Sep 16 2019
  • Mathematica
    multsubs[set_,k_]:=If[k==0,{{}},Join@@Table[Prepend[#,set[[i]]]&/@multsubs[Drop[set,i-1],k-1],{i,Length[set]}]];
    prs2mat[prs_]:=Table[Count[prs,{i,j}],{i,Union[First/@prs]},{j,Union[Last/@prs]}];
    Table[Length[Select[multsubs[Tuples[Range[n],2],n],And[Union[First/@#]==Range[Max@@First/@#],Union[Last/@#]==Range[Max@@Last/@#],UnsameQ@@prs2mat[#]]&]],{n,5}]

Extensions

a(7)-a(20) from Alois P. Heinz, Sep 16 2019
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