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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A319644 Number of non-isomorphic weight-n antichains of distinct multisets whose dual is also an antichain of distinct multisets.

Original entry on oeis.org

1, 1, 2, 3, 5, 8, 18, 31, 73, 162, 413
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(5) = 8 antichains:
1: {{1}}
2: {{1,1}}
   {{1},{2}}
3: {{1,1,1}}
   {{1},{2,2}}
   {{1},{2},{3}}
4: {{1,1,1,1}}
   {{1},{2,2,2}}
   {{1,1},{2,2}}
   {{1},{2},{3,3}}
   {{1},{2},{3},{4}}
5: {{1,1,1,1,1}}
   {{1},{2,2,2,2}}
   {{1,1},{1,2,2}}
   {{1,1},{2,2,2}}
   {{1},{2},{3,3,3}}
   {{1},{2,2},{3,3}}
   {{1},{2},{3},{4,4}}
   {{1},{2},{3},{4},{5}}
		

Crossrefs

Formula

Euler transform of A319629.

A322846 Squarefree numbers whose prime indices have no equivalent primes.

Original entry on oeis.org

1, 2, 3, 5, 6, 7, 10, 11, 14, 15, 17, 19, 21, 22, 23, 30, 31, 33, 34, 35, 37, 38, 39, 41, 42, 46, 51, 53, 55, 57, 59, 61, 62, 65, 66, 67, 69, 70, 71, 74, 77, 78, 82, 83, 85, 87, 89, 91, 93, 95, 97, 102, 103, 105, 106, 107, 109, 110, 111, 114, 115, 118, 119
Offset: 1

Views

Author

Gus Wiseman, Dec 28 2018

Keywords

Comments

A prime index of n is a number m such that prime(m) divides n. The multiset of prime indices of n is row n of A112798.
In an integer partition, two primes are equivalent if each part has in its prime factorization the same multiplicity of both primes. For example, in (6,5) the primes {2,3} are equivalent while {2,5} and {3,5} are not. In (30,6) also, the primes {2,3} are equivalent, while {2,5} and {3,5} are not.
Also MM-numbers of strict T_0 multiset multisystems. A multiset multisystem is a finite multiset of finite multisets. The multiset multisystem with MM-number n is formed by taking the multiset of prime indices of each part of the multiset of prime indices of n. For example, the prime indices of 78 are {1,2,6}, so the multiset multisystem with MM-number 78 is {{},{1},{1,2}}. The dual of a multiset multisystem has, for each vertex, one block 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 T_0 condition means the dual is strict (no repeated parts).

Examples

			The sequence of all strict T_0 multiset multisystems together with their MM-numbers begins:
   1: {}
   2: {{}}
   3: {{1}}
   5: {{2}}
   6: {{},{1}}
   7: {{1,1}}
  10: {{},{2}}
  11: {{3}}
  14: {{},{1,1}}
  15: {{1},{2}}
  17: {{4}}
  19: {{1,1,1}}
  21: {{1},{1,1}}
  22: {{},{3}}
  23: {{2,2}}
  30: {{},{1},{2}}
  31: {{5}}
  33: {{1},{3}}
  34: {{},{4}}
  35: {{2},{1,1}}
  37: {{1,1,2}}
  38: {{},{1,1,1}}
  39: {{1},{1,2}}
		

Crossrefs

Programs

  • Mathematica
    primeMS[n_]:=If[n==1,{},Flatten[Cases[FactorInteger[n],{p_,k_}:>Table[PrimePi[p],{k}]]]];
    dual[eds_]:=Table[First/@Position[eds,x],{x,Union@@eds}];
    Select[Range[100],And[SquareFreeQ[#],UnsameQ@@dual[primeMS/@primeMS[#]]]&]

A319618 Number of non-isomorphic weight-n antichains of multisets whose dual is a chain of multisets.

Original entry on oeis.org

1, 1, 3, 4, 9, 10, 24, 28, 57, 80, 138
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(4) = 9 antichains:
1: {{1}}
2: {{1,1}}
   {{1,2}}
   {{1},{1}}
3: {{1,1,1}}
   {{1,2,2}}
   {{1,2,3}}
   {{1},{1},{1}}
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}}
   {{1,2},{1,2}}
   {{1,2},{2,2}}
   {{1},{1},{1},{1}}
		

Crossrefs

A319619 Number of non-isomorphic connected weight-n antichains of multisets whose dual is also an antichain of multisets.

Original entry on oeis.org

1, 1, 3, 3, 6, 4, 15, 13, 48, 96, 280
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(5) = 4 antichains:
1: {{1}}
2: {{1,1}}
   {{1,2}}
   {{1},{1}}
3: {{1,1,1}}
   {{1,2,3}}
   {{1},{1},{1}}
4: {{1,1,1,1}}
   {{1,1,2,2}}
   {{1,2,3,4}}
   {{1,1},{1,1}}
   {{1,2},{1,2}}
   {{1},{1},{1},{1}}
5: {{1,1,1,1,1}}
   {{1,2,3,4,5}}
   {{1,1},{1,2,2}}
   {{1},{1},{1},{1},{1}}
		

Crossrefs

Formula

Euler transform is A318099.

A319623 Number of connected antichain covers of n vertices by distinct sets whose dual is also an antichain of distinct sets.

Original entry on oeis.org

1, 1, 0, 1, 15, 1957
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}}.

Examples

			Non-isomorphic representatives of the a(1) = 1 through a(4) = 15 antichain covers:
1: {{1}}
3: {{1,2},{1,3},{2,3}}
4: {{1,2},{1,3},{2,4},{3,4}}
   {{1,3},{1,4},{2,3},{2,4}}
   {{1,2},{1,4},{2,3},{3,4}}
   {{1,4},{2,4},{3,4},{1,2,3}}
   {{1,3},{2,3},{3,4},{1,2,4}}
   {{1,2},{2,3},{2,4},{1,3,4}}
   {{1,2},{1,3},{1,4},{2,3,4}}
   {{1,3},{1,4},{2,3},{2,4},{3,4}}
   {{1,2},{1,4},{2,3},{2,4},{3,4}}
   {{1,2},{1,3},{2,3},{2,4},{3,4}}
   {{1,2},{1,3},{1,4},{2,4},{3,4}}
   {{1,2},{1,3},{1,4},{2,3},{3,4}}
   {{1,2},{1,3},{1,4},{2,3},{2,4}}
   {{1,2,3},{1,2,4},{1,3,4},{2,3,4}}
   {{1,2},{1,3},{1,4},{2,3},{2,4},{3,4}}
		

Crossrefs

A319624 Number of non-isomorphic connected antichain covers of n vertices by distinct sets whose dual is also an antichain of distinct sets.

Original entry on oeis.org

1, 1, 0, 1, 5, 63
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}}.

Examples

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

Crossrefs

A319631 Number of non-isomorphic weight-n antichains of multisets whose dual is a chain of distinct multisets.

Original entry on oeis.org

1, 1, 2, 3, 5, 5, 13, 11, 25, 31, 54
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(5) = 5 antichains:
1: {{1}}
2: {{1,1}}
   {{1},{1}}
3: {{1,1,1}}
   {{1,2,2}}
   {{1},{1},{1}}
4: {{1,1,1,1}}
   {{1,2,2,2}}
   {{1,1},{1,1}}
   {{1,2},{2,2}}
   {{1},{1},{1},{1}}
5: {{1,1,1,1,1}}
   {{1,1,2,2,2}}
   {{1,2,2,2,2}}
   {{1,2},{2,2,2}}
   {{1},{1},{1},{1},{1}}
		

Crossrefs

A319632 Number of non-isomorphic weight-n antichains of (not necessarily distinct) sets whose dual is also an antichain of (not necessarily distinct) sets.

Original entry on oeis.org

1, 1, 3, 5, 11, 17, 35, 53, 100, 154, 275
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(4) = 11 set systems:
1: {{1}}
2: {{1,2}}
   {{1},{1}}
   {{1},{2}}
3: {{1,2,3}}
   {{1},{2,3}}
   {{1},{1},{1}}
   {{1},{2},{2}}
   {{1},{2},{3}}
4: {{1,2,3,4}}
   {{1},{2,3,4}}
   {{1,2},{1,2}}
   {{1,2},{3,4}}
   {{1},{1},{2,3}}
   {{1},{2},{3,4}}
   {{1},{1},{1},{1}}
   {{1},{1},{2},{2}}
   {{1},{2},{2},{2}}
   {{1},{2},{3},{3}}
   {{1},{2},{3},{4}}
		

Crossrefs

A319633 Number of antichain covers of n vertices by distinct sets whose dual is also an antichain of (not necessarily distinct) sets.

Original entry on oeis.org

1, 1, 2, 6, 40, 2309
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}}.

Examples

			The a(3) = 6 antichain covers:
   {{1,2,3}}
   {{3},{1,2}}
   {{2},{1,3}}
   {{1},{2,3}}
   {{1},{2},{3}}
   {{1,2},{1,3},{2,3}}
		

Crossrefs

A319634 Number of non-isomorphic antichain covers of n vertices by distinct sets whose dual is also an antichain of (not necessarily distinct) sets.

Original entry on oeis.org

1, 1, 2, 4, 12, 87
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}}.

Examples

			Non-isomorphic representatives of the a(1) = 1 through a(4) = 12 antichain covers:
  {{1}}   {{1,2}}     {{1,2,3}}              {{1,2,3,4}}
         {{1},{2}}   {{1},{2,3}}            {{1},{2,3,4}}
                    {{1},{2},{3}}           {{1,2},{3,4}}
                 {{1,2},{1,3},{2,3}}       {{1},{2},{3,4}}
                                          {{1},{2},{3},{4}}
                                       {{1,2},{1,3,4},{2,3,4}}
                                       {{1},{2,3},{2,4},{3,4}}
                                      {{1,2},{1,3},{2,4},{3,4}}
                                     {{1,2},{1,3},{1,4},{2,3,4}}
                                   {{1,3},{1,4},{2,3},{2,4},{3,4}}
                                  {{1,2,3},{1,2,4},{1,3,4},{2,3,4}}
                                {{1,2},{1,3},{1,4},{2,3},{2,4},{3,4}}
		

Crossrefs

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