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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A321413 Number of non-isomorphic self-dual multiset partitions of weight n with no singletons and relatively prime part sizes.

Original entry on oeis.org

1, 0, 0, 0, 0, 3, 0, 14, 13, 50, 65
Offset: 0

Views

Author

Gus Wiseman, Nov 16 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, with relatively prime row sums (or column sums) and no row (or column) summing 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(5) = 3, a(7) = 14, and a(8) = 13 multiset partitions:
  {{11}{122}}  {{111}{1222}}    {{111}{11222}}
  {{11}{222}}  {{111}{2222}}    {{111}{22222}}
  {{12}{122}}  {{112}{1222}}    {{112}{12222}}
               {{11}{22222}}    {{122}{11222}}
               {{12}{12222}}    {{11}{122}{233}}
               {{122}{1122}}    {{11}{122}{333}}
               {{22}{11222}}    {{11}{222}{333}}
               {{11}{12}{233}}  {{11}{223}{233}}
               {{11}{22}{233}}  {{12}{122}{333}}
               {{11}{22}{333}}  {{12}{123}{233}}
               {{11}{23}{233}}  {{13}{112}{233}}
               {{12}{12}{333}}  {{13}{122}{233}}
               {{12}{13}{233}}  {{23}{123}{123}}
               {{13}{23}{123}}
		

Crossrefs

A321412 Number of non-isomorphic self-dual multiset partitions of weight n with no singletons and with aperiodic parts.

Original entry on oeis.org

1, 0, 0, 0, 1, 1, 3, 4, 12, 20, 42
Offset: 0

Views

Author

Gus Wiseman, Nov 16 2018

Keywords

Comments

A multiset is aperiodic if its multiplicities are relatively prime.
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, with no row or column having a common divisor > 1 or summing 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(5) = 1 through a(8) = 12 multiset partitions:
{{12}{12}}  {{12}{122}}  {{112}{122}}    {{112}{1222}}    {{1112}{1222}}
                         {{12}{1222}}    {{12}{12222}}    {{112}{12222}}
                         {{12}{13}{23}}  {{12}{13}{233}}  {{12}{122222}}
                                         {{13}{23}{123}}  {{122}{11222}}
                                                          {{12}{123}{233}}
                                                          {{12}{13}{2333}}
                                                          {{13}{112}{233}}
                                                          {{13}{122}{233}}
                                                          {{13}{23}{1233}}
                                                          {{23}{123}{123}}
                                                          {{12}{12}{34}{34}}
                                                          {{12}{13}{24}{34}}
		

Crossrefs

A323581 Number of ways to fill a Young diagram with positive integers summing to n such that the rows are strictly increasing and the columns are strictly decreasing.

Original entry on oeis.org

1, 1, 1, 3, 3, 5, 8, 10, 14, 19, 28, 34, 48, 60, 80, 106, 134, 171, 222, 279, 354, 452, 562, 706, 884, 1100
Offset: 0

Views

Author

Gus Wiseman, Jan 18 2019

Keywords

Examples

			The a(8) = 14 tableaux:
  8   1 7   2 6   3 5   1 2 5   1 3 4
.
  7   6   5   2 5   3 4   2 3
  1   2   3   1     1     1 2
.
  5   4
  2   3
  1   1
		

Crossrefs

Programs

  • Mathematica
    primeMS[n_]:=If[n==1,{},Flatten[Cases[FactorInteger[n],{p_,k_}:>Table[PrimePi[p],{k}]]]];
    sqfacs[n_]:=If[n<=1,{{}},Join@@Table[Map[Prepend[#,d]&,Select[sqfacs[n/d],Min@@#>=d&]],{d,Select[Rest[Divisors[n]],SquareFreeQ]}]];
    Table[Sum[Length[Select[Reverse/@Sort/@Map[primeMS,sqfacs[y],{2}],And@@Greater@@@DeleteCases[Transpose[PadRight[#]],0,{2}]&]],{y,Times@@Prime/@#&/@IntegerPartitions[n]}],{n,10}]

A321484 Number of non-isomorphic self-dual connected multiset partitions of weight n.

Original entry on oeis.org

1, 1, 1, 2, 3, 6, 9, 20, 35, 78, 141
Offset: 0

Views

Author

Gus Wiseman, Nov 16 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.

Examples

			Non-isomorphic representatives of the a(1) = 1 through a(6) = 9 multiset partitions:
  {{1}}  {{11}}  {{111}}    {{1111}}    {{11111}}      {{111111}}
                 {{2}{12}}  {{12}{12}}  {{11}{122}}    {{112}{122}}
                            {{2}{122}}  {{12}{122}}    {{12}{1222}}
                                        {{2}{1222}}    {{2}{12222}}
                                        {{2}{13}{23}}  {{22}{1122}}
                                        {{3}{3}{123}}  {{12}{13}{23}}
                                                       {{2}{13}{233}}
                                                       {{3}{23}{123}}
                                                       {{3}{3}{1233}}
		

Crossrefs

Previous Showing 41-44 of 44 results.