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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A321155 Regular triangle where T(n,k) is the number of non-isomorphic connected multiset partitions of weight n with density -1 <= k < n-2.

Original entry on oeis.org

1, 2, 1, 3, 2, 1, 6, 6, 4, 1, 10, 14, 11, 4, 1, 22, 38, 38, 20, 6, 1, 42, 94, 111, 72, 28, 6, 1, 94, 250, 348, 278, 138, 42, 8, 1, 203, 648, 1044, 992, 596, 226, 56, 8, 1, 470, 1728, 3192, 3538, 2536, 1192, 370, 76, 10, 1
Offset: 1

Views

Author

Gus Wiseman, Oct 29 2018

Keywords

Comments

The density of a multiset partition of weight n with e parts and v vertices is n - e - v. The weight of a multiset partition is the sum of sizes of its parts.

Examples

			Triangle begins:
    1
    2    1
    3    2    1
    6    6    4    1
   10   14   11    4    1
   22   38   38   20    6    1
   42   94  111   72   28    6    1
   94  250  348  278  138   42    8    1
  203  648 1044  992  596  226   56    8    1
  470 1728 3192 3538 2536 1192  370   76   10    1
Non-isomorphic representatives of the connected multiset partitions counted in row 5:
{1,2,3,4,5}         {1,2,3,4,4}       {1,2,2,3,3}     {1,1,2,2,2}   {1,1,1,1,1}
{1,4},{2,3,4}       {1,2},{2,3,3}     {1,2,3,3,3}     {1,2,2,2,2}
{4},{1,2,3,4}       {1,3},{2,3,3}     {1,1},{1,2,2}   {1},{1,1,1,1}
{2},{1,3},{2,3}     {2},{1,2,3,3}     {1},{1,2,2,2}   {1,1},{1,1,1}
{2},{3},{1,2,3}     {2,3},{1,2,3}     {1,2},{1,2,2}
{3},{1,3},{2,3}     {3},{1,2,3,3}     {1,2},{2,2,2}
{3},{3},{1,2,3}     {3,3},{1,2,3}     {2},{1,1,2,2}
{1},{2},{2},{1,2}   {1},{1},{1,2,2}   {2},{1,2,2,2}
{2},{2},{2},{1,2}   {1},{1,2},{2,2}   {2,2},{1,2,2}
{1},{1},{1},{1},{1} {1},{2},{1,2,2}   {1},{1},{1,1,1}
                    {2},{1,2},{1,2}   {1},{1,1},{1,1}
                    {2},{1,2},{2,2}
                    {2},{2},{1,2,2}
                    {1},{1},{1},{1,1}
		

Crossrefs

First column is A125702. Row sums are A007718.

A319560 Number of non-isomorphic strict T_0 multiset partitions of weight n.

Original entry on oeis.org

1, 1, 2, 6, 15, 40, 121, 353, 1107, 3550, 11818
Offset: 0

Views

Author

Gus Wiseman, Sep 23 2018

Keywords

Comments

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. The T_0 condition means that there are no equivalent vertices.
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(4) = 15 multiset partitions:
1: {{1}}
2: {{1,1}}
   {{1},{2}}
3: {{1,1,1}}
   {{1,2,2}}
   {{1},{1,1}}
   {{1},{2,2}}
   {{2},{1,2}}
   {{1},{2},{3}}
4: {{1,1,1,1}}
   {{1,2,2,2}}
   {{1},{1,1,1}}
   {{1},{1,2,2}}
   {{1},{2,2,2}}
   {{1},{2,3,3}}
   {{2},{1,2,2}}
   {{1,1},{2,2}}
   {{1,2},{2,2}}
   {{1,3},{2,3}}
   {{1},{2},{1,2}}
   {{1},{2},{2,2}}
   {{1},{2},{3,3}}
   {{1},{3},{2,3}}
   {{1},{2},{3},{4}}
		

Crossrefs

A319566 Number of non-isomorphic connected T_0 set systems of weight n.

Original entry on oeis.org

1, 1, 0, 1, 2, 3, 8, 17, 41, 103, 276
Offset: 0

Views

Author

Gus Wiseman, Sep 23 2018

Keywords

Comments

In a set system, two vertices are equivalent if in every block the presence of the first is equivalent to the presence of the second. The T_0 condition means that there are no equivalent vertices.
The weight of a set system 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(6) = 8 set systems:
1:        {{1}}
3:     {{2},{1,2}}
4:    {{1,3},{2,3}}
     {{1},{2},{1,2}}
5:  {{2},{3},{1,2,3}}
    {{2},{1,3},{2,3}}
    {{3},{1,3},{2,3}}
6: {{3},{1,4},{2,3,4}}
   {{3},{2,3},{1,2,3}}
   {{1,2},{1,3},{2,3}}
   {{1,3},{2,4},{3,4}}
   {{1,4},{2,4},{3,4}}
  {{1},{2},{3},{1,2,3}}
  {{1},{2},{1,3},{2,3}}
  {{2},{3},{1,3},{2,3}}
		

Crossrefs

A320356 Number of strict connected antichains of multisets whose multiset union is an integer partition of n.

Original entry on oeis.org

1, 1, 2, 3, 5, 8, 13, 22, 35, 62, 98, 171, 277
Offset: 0

Views

Author

Gus Wiseman, Oct 11 2018

Keywords

Examples

			The a(1) = 1 through a(6) = 13 clutters:
  {{1}}  {{2}}    {{3}}      {{4}}        {{5}}          {{6}}
         {{1,1}}  {{1,2}}    {{1,3}}      {{1,4}}        {{1,5}}
                  {{1,1,1}}  {{2,2}}      {{2,3}}        {{2,4}}
                             {{1,1,2}}    {{1,1,3}}      {{3,3}}
                             {{1,1,1,1}}  {{1,2,2}}      {{1,1,4}}
                                          {{1,1,1,2}}    {{1,2,3}}
                                          {{1,1,1,1,1}}  {{2,2,2}}
                                          {{1,1},{1,2}}  {{1,1,1,3}}
                                                         {{1,1,2,2}}
                                                         {{1,1,1,1,2}}
                                                         {{1,1},{1,3}}
                                                         {{1,1,1,1,1,1}}
                                                         {{1,2},{1,1,1}}
		

Crossrefs

Programs

  • Mathematica
    sps[{}]:={{}};sps[set:{i_,_}]:=Join@@Function[s,Prepend[#,s]&/@sps[Complement[set,s]]]/@Cases[Subsets[set],{i,_}];
    mps[set_]:=Union[Sort[Sort/@(#/.x_Integer:>set[[x]])]&/@sps[Range[Length[set]]]];
    csm[s_]:=With[{c=Select[Tuples[Range[Length[s]],2],And[OrderedQ[#],UnsameQ@@#,Length[Intersection@@s[[#]]]>0]&]},If[c=={},s,csm[Union[Append[Delete[s,List/@c[[1]]],Union@@s[[c[[1]]]]]]]]];
    submultisetQ[M_,N_]:=Or[Length[M]==0,MatchQ[{Sort[List@@M],Sort[List@@N]},{{x_,Z___},{_,x_,W___}}/;submultisetQ[{Z},{W}]]];
    antiQ[s_]:=Select[Tuples[s,2],And[UnsameQ@@#,submultisetQ@@#]&]=={};
    Table[Length[Select[Join@@mps/@IntegerPartitions[n],And[UnsameQ@@#,Length[csm[#]]==1,antiQ[#]]&]],{n,8}]

A321585 Number of connected nonnegative integer matrices with sum of entries equal to n and no zero rows or columns.

Original entry on oeis.org

1, 1, 3, 11, 52, 312, 2290, 19920, 200522, 2293677, 29389005, 416998371, 6490825772, 109972169413, 2014696874717, 39684502845893, 836348775861331, 18777970539419957, 447471215460930665, 11279275874429302811, 299844572529989373703, 8383794111721619471384, 245956060268568277412668
Offset: 0

Views

Author

Gus Wiseman, Nov 13 2018

Keywords

Comments

A matrix is connected if the positions in each row (or each column) of the nonzero entries form a connected hypergraph.

Examples

			The a(3) = 11 matrices:
  [3] [2 1] [1 2] [1 1 1]
.
  [2] [1 1] [1 1] [1] [1 0] [0 1]
  [1] [1 0] [0 1] [2] [1 1] [1 1]
.
  [1]
  [1]
  [1]
		

Crossrefs

Programs

  • Mathematica
    multsubs[set_,k_]:=If[k==0,{{}},Join@@Table[Prepend[#,set[[i]]]&/@multsubs[Drop[set,i-1],k-1],{i,Length[set]}]];
    csm[s_]:=With[{c=Select[Tuples[Range[Length[s]],2],And[OrderedQ[#],UnsameQ@@#,Length[Intersection@@s[[#]]]>0]&]},If[c=={},s,csm[Union[Append[Delete[s,List/@c[[1]]],Union@@s[[c[[1]]]]]]]]];
    Table[Length[Select[multsubs[Tuples[Range[n],2],n],And[Union[First/@#]==Range[Max@@First/@#],Union[Last/@#]==Range[Max@@Last/@#],Length[csm[Map[Last,GatherBy[#,First],{2}]]]==1]&]],{n,5}] (* Mathematica 7.0+ *)
  • PARI
    NonZeroCols(M)={my(C=Vec(M)); Mat(vector(#C, n,  sum(k=1, n, (-1)^(n-k)*binomial(n,k)*C[k])))}
    ConnectedMats(M)={my([m,n]=matsize(M), R=matrix(m,n)); for(m=1, m, for(n=1, n, R[m,n] = M[m,n] - sum(i=1, m-1, sum(j=1, n-1, binomial(m-1,i-1)*binomial(n,j)*R[i,j]*M[m-i,n-j])))); R}
    seq(n)={my(M=matrix(n,n,i,j,sum(k=1, n, binomial(i*j+k-1,k)*x^k, O(x*x^n) ))); Vec(1 + vecsum(vecsum(Vec( ConnectedMats( NonZeroCols( NonZeroCols(M)~))))))} \\ Andrew Howroyd, Jan 17 2024

Extensions

a(7) onwards from Andrew Howroyd, Jan 17 2024

A319790 Number of non-isomorphic connected multiset partitions of weight n with empty intersection.

Original entry on oeis.org

1, 0, 0, 0, 1, 5, 32, 134, 588, 2335, 9335, 36506, 144263, 571238, 2291894, 9300462, 38303796, 160062325, 679333926, 2927951665, 12817221628, 56974693933, 257132512297, 1177882648846, 5475237760563, 25818721638720, 123473772356785, 598687942799298, 2942344764127039
Offset: 0

Views

Author

Gus Wiseman, Sep 27 2018

Keywords

Comments

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(4) = 1 through a(5) = 5 connected multiset partitions:
4:  {{1},{2},{1,2}}
5: {{1},{2},{1,2,2}}
   {{1},{1,2},{2,2}}
   {{2},{3},{1,2,3}}
   {{2},{1,3},{2,3}}
  {{1},{2},{2},{1,2}}
		

Crossrefs

Formula

a(n) = A007718(n) - A007716(n) + A317757(n). - Andrew Howroyd, May 31 2023

Extensions

Terms a(11) and beyond from Andrew Howroyd, May 31 2023

A319791 Number of non-isomorphic connected set multipartitions (multisets of sets) of weight n with empty intersection.

Original entry on oeis.org

1, 0, 0, 0, 1, 3, 14, 38, 125, 360, 1107, 3297, 10292, 32134, 103759, 340566, 1148150, 3951339, 13925330, 50122316, 184365292, 692145409, 2651444318, 10356184440, 41224744182, 167150406897, 689998967755, 2898493498253, 12384852601731, 53804601888559, 237566072006014
Offset: 0

Views

Author

Gus Wiseman, Sep 27 2018

Keywords

Comments

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(4) = 1 through a(6) = 14 set multipartitions:
4:    {{1},{2},{1,2}}
5:   {{2},{3},{1,2,3}}
     {{2},{1,3},{2,3}}
    {{1},{2},{2},{1,2}}
6:  {{1},{1,4},{2,3,4}}
    {{1},{2,3},{1,2,3}}
    {{3},{4},{1,2,3,4}}
    {{3},{1,4},{2,3,4}}
    {{1,2},{1,3},{2,3}}
    {{1,3},{2,4},{3,4}}
   {{1},{2},{3},{1,2,3}}
   {{1},{2},{1,2},{1,2}}
   {{1},{2},{1,3},{2,3}}
   {{2},{2},{1,3},{2,3}}
   {{2},{3},{3},{1,2,3}}
   {{2},{3},{1,3},{2,3}}
  {{1},{1},{2},{2},{1,2}}
  {{1},{2},{2},{2},{1,2}}
		

Crossrefs

Formula

a(n) = A056156(n) - A049311(n) + A319748(n). - Andrew Howroyd, May 31 2023

Extensions

Terms a(11) and beyond from Andrew Howroyd, May 31 2023

A322110 Number of non-isomorphic connected multiset partitions of weight n that cannot be capped by a tree.

Original entry on oeis.org

1, 1, 3, 6, 15, 32, 86, 216, 628, 1836, 5822
Offset: 0

Views

Author

Gus Wiseman, Nov 26 2018

Keywords

Comments

The weight of a multiset partition is the sum of sizes of its parts. Weight is generally not the same as number of vertices.
The density of a multiset partition is defined to be the sum of numbers of distinct elements in each part, minus the number of parts, minus the total number of distinct elements in the whole partition. A multiset partition is a tree if it has more than one part, is connected, and has density -1. A cap is a certain kind of non-transitive coarsening of a multiset partition. For example, the four caps of {{1,1},{1,2},{2,2}} are {{1,1},{1,2},{2,2}}, {{1,1},{1,2,2}}, {{1,1,2},{2,2}}, {{1,1,2,2}}. - Gus Wiseman, Feb 05 2021

Examples

			The multiset partition C = {{1,1},{1,2,3},{2,3,3}} is not a tree but has the cap {{1,1},{1,2,3,3}} which is a tree, so C is not counted under a(8).
Non-isomorphic representatives of the a(1) = 1 through a(5) = 32 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}}        {{1,1,2,2,2}}
         {{1},{1}}  {{1,2,3}}      {{1,2,2,2}}        {{1,2,2,2,2}}
                    {{1},{1,1}}    {{1,2,3,3}}        {{1,2,2,3,3}}
                    {{2},{1,2}}    {{1,2,3,4}}        {{1,2,3,3,3}}
                    {{1},{1},{1}}  {{1},{1,1,1}}      {{1,2,3,4,4}}
                                   {{1,1},{1,1}}      {{1,2,3,4,5}}
                                   {{1},{1,2,2}}      {{1},{1,1,1,1}}
                                   {{1,2},{1,2}}      {{1,1},{1,1,1}}
                                   {{2},{1,2,2}}      {{1},{1,2,2,2}}
                                   {{3},{1,2,3}}      {{1,2},{1,2,2}}
                                   {{1},{1},{1,1}}    {{2},{1,1,2,2}}
                                   {{1},{2},{1,2}}    {{2},{1,2,2,2}}
                                   {{2},{2},{1,2}}    {{2},{1,2,3,3}}
                                   {{1},{1},{1},{1}}  {{2,2},{1,2,2}}
                                                      {{2,3},{1,2,3}}
                                                      {{3},{1,2,3,3}}
                                                      {{4},{1,2,3,4}}
                                                      {{1},{1},{1,1,1}}
                                                      {{1},{1,1},{1,1}}
                                                      {{1},{1},{1,2,2}}
                                                      {{1},{2},{1,2,2}}
                                                      {{2},{1,2},{1,2}}
                                                      {{2},{1,2},{2,2}}
                                                      {{2},{2},{1,2,2}}
                                                      {{2},{3},{1,2,3}}
                                                      {{3},{1,3},{2,3}}
                                                      {{3},{3},{1,2,3}}
                                                      {{1},{1},{1},{1,1}}
                                                      {{1},{2},{2},{1,2}}
                                                      {{2},{2},{2},{1,2}}
                                                      {{1},{1},{1},{1},{1}}
		

Crossrefs

Non-isomorphic tree multiset partitions are counted by A321229.
The weak-antichain case is counted by A322117.
The case without singletons is counted by A322118.

Extensions

Corrected by Gus Wiseman, Jan 27 2021

A319629 Number of non-isomorphic connected weight-n antichains of distinct multisets whose dual is also an antichain of distinct multisets.

Original entry on oeis.org

1, 1, 1, 1, 1, 2, 7, 9, 29, 66, 189
Offset: 0

Views

Author

Gus Wiseman, Sep 25 2018

Keywords

Comments

The dual of a multiset partition has, for each vertex, one block consisting of the indices (or positions) of the blocks 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(1) = 1 through a(7) = 9 antichains:
1: {{1}}
2: {{1,1}}
3: {{1,1,1}}
4: {{1,1,1,1}}
5: {{1,1,1,1,1}}
   {{1,1},{1,2,2}}
6: {{1,1,1,1,1,1}}
   {{1,1},{1,2,2,2}}
   {{1,1,2},{1,2,2}}
   {{1,1,2},{2,2,2}}
   {{1,1,2},{2,3,3}}
   {{1,1},{1,2},{2,2}}
   {{1,2},{1,3},{2,3}}
7: {{1,1,1,1,1,1,1}}
   {{1,1},{1,2,2,2,2}}
   {{1,1,1},{1,2,2,2}}
   {{1,1,2},{1,2,2,2}}
   {{1,1,2},{2,2,2,2}}
   {{1,1,2},{2,3,3,3}}
   {{1,1},{1,2},{2,2,2}}
   {{1,1},{1,2},{2,3,3}}
   {{1,2},{1,3},{2,3,3}}
		

Crossrefs

Formula

Euler transform is A319644.

A320351 Number of connected multiset partitions of integer partitions of n.

Original entry on oeis.org

1, 1, 3, 5, 11, 18, 38, 66, 130, 237, 449, 823, 1538
Offset: 0

Views

Author

Gus Wiseman, Oct 11 2018

Keywords

Examples

			The a(1) = 1 through a(5) = 18 multiset partitions:
  {{1}}  {{2}}      {{3}}          {{4}}              {{5}}
         {{1,1}}    {{1,2}}        {{1,3}}            {{1,4}}
         {{1},{1}}  {{1,1,1}}      {{2,2}}            {{2,3}}
                    {{1},{1,1}}    {{1,1,2}}          {{1,1,3}}
                    {{1},{1},{1}}  {{2},{2}}          {{1,2,2}}
                                   {{1,1,1,1}}        {{1,1,1,2}}
                                   {{1},{1,2}}        {{1},{1,3}}
                                   {{1},{1,1,1}}      {{2},{1,2}}
                                   {{1,1},{1,1}}      {{1,1,1,1,1}}
                                   {{1},{1},{1,1}}    {{1},{1,1,2}}
                                   {{1},{1},{1},{1}}  {{1,1},{1,2}}
                                                      {{1},{1,1,1,1}}
                                                      {{1,1},{1,1,1}}
                                                      {{1},{1},{1,2}}
                                                      {{1},{1},{1,1,1}}
                                                      {{1},{1,1},{1,1}}
                                                      {{1},{1},{1},{1,1}}
                                                      {{1},{1},{1},{1},{1}}
		

Crossrefs

Programs

  • Mathematica
    sps[{}]:={{}};sps[set:{i_,_}]:=Join@@Function[s,Prepend[#,s]&/@sps[Complement[set,s]]]/@Cases[Subsets[set],{i,_}];
    mps[set_]:=Union[Sort[Sort/@(#/.x_Integer:>set[[x]])]&/@sps[Range[Length[set]]]];
    csm[s_]:=With[{c=Select[Tuples[Range[Length[s]],2],And[OrderedQ[#],UnsameQ@@#,Length[Intersection@@s[[#]]]>0]&]},If[c=={},s,csm[Union[Append[Delete[s,List/@c[[1]]],Union@@s[[c[[1]]]]]]]]];
    Table[Length[Select[Join@@mps/@IntegerPartitions[n],Length[csm[#]]==1&]],{n,8}]
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