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 11-16 of 16 results.

A299966 Number of normal generalized Young tableaux, of shape the integer partition with Heinz number n, with all rows and columns weakly increasing and all regions non-singleton skew-partitions.

Original entry on oeis.org

1, 0, 1, 1, 1, 1, 2, 1, 3, 3, 3, 3, 5, 5, 5, 2, 8, 5, 13, 6, 13, 10, 21, 5, 11, 18, 11, 14, 34, 15, 55, 3, 26, 33, 23, 13, 89, 59, 54, 14, 144, 38, 233, 28, 31, 105, 377, 10, 47, 31, 106, 57, 610, 23, 60, 32, 206, 185, 987, 38, 1597, 324, 91, 5, 132, 93, 2584, 111
Offset: 1

Views

Author

Gus Wiseman, Feb 22 2018

Keywords

Comments

A generalized Young tableau of shape y is an array obtained by replacing the dots in the Ferrers diagram of y with positive integers. A tableau is normal if its entries span an initial interval of positive integers. The Heinz number of an integer partition (y_1,...,y_k) is prime(y_1)*...*prime(y_k).

Examples

			The a(25) = 11 tableaux:
1 2 3   1 2 2   1 1 3   1 1 2
1 2 3   1 3 3   2 2 3   2 3 3
.
1 2 2   1 1 2   1 1 2   1 1 2   1 1 1   1 1 1
1 2 2   2 2 2   1 2 2   1 1 2   2 2 2   1 2 2
.
1 1 1
1 1 1
		

References

  • Bruce E. Sagan, The Symmetric Group, Springer-Verlag New York, 2001.

Crossrefs

Programs

  • Mathematica
    primeMS[n_]:=If[n===1,{},Flatten[Cases[FactorInteger[n],{p_,k_}:>Table[PrimePi[p],{k}]]]];
    undptns[y_]:=DeleteCases[Select[Tuples[Range[0,#]&/@y],OrderedQ[#,GreaterEqual]&],0,{2}];
    eh[y_]:=If[Total[y]=!=1,1,0]+Sum[eh[c],{c,Select[undptns[y],Total[#]>1&&Total[y]-Total[#]>1&]}];
    Table[eh[Reverse[primeMS[n]]],{n,60}]

A285175 Number of normal generalized Young tableaux, of shape the integer partition with Heinz number n, with all rows and columns strictly increasing.

Original entry on oeis.org

1, 1, 1, 1, 1, 3, 1, 1, 3, 5, 1, 5, 1, 7, 11, 1, 1, 11, 1, 13, 23, 9, 1, 7, 11, 11, 11, 25, 1, 51, 1, 1, 39, 13, 45, 23, 1, 15, 59, 25, 1, 135, 1, 41, 73, 17, 1, 9, 45, 73, 83, 61, 1, 45, 107, 63, 111, 19, 1, 135, 1, 21, 259, 1, 205, 279, 1, 85, 143, 349, 1
Offset: 1

Views

Author

Gus Wiseman, Feb 26 2018

Keywords

Comments

A generalized Young tableau of shape y is an array obtained by replacing the dots in the Ferrers diagram of y with positive integers. A tableau is normal if its entries span an initial interval of positive integers. The Heinz number of an integer partition (y_1,...,y_k) is prime(y_1)*...*prime(y_k).

Examples

			The a(15) = 11 tableaux:
1 2 3   1 2 4   1 3 4   1 2 5   1 3 5
4 5     3 5     2 5     3 4     2 4
.
1 2 3   1 2 3   1 2 4   1 2 4   1 3 4
2 4     3 4     2 3     3 4     2 4
.
1 2 3
2 3
		

Crossrefs

Programs

  • Mathematica
    a[n_]:=If[n===1,1,Sum[a[n/q*Times@@Cases[FactorInteger[q],{p_,k_}:>If[p===2,1,NextPrime[p,-1]^k]]],{q,Select[Rest[Divisors[n]],SquareFreeQ]}]];
    Array[a,100]

A299967 Number of normal generalized Young tableaux of size n with all rows and columns weakly increasing and all regions non-singleton skew-partitions.

Original entry on oeis.org

1, 0, 2, 3, 13, 32, 121, 376, 1406, 5030, 19632, 76334, 314582, 1308550, 5667494, 24940458, 113239394, 523149560, 2480434938, 11968944532, 59051754824
Offset: 0

Views

Author

Gus Wiseman, Feb 22 2018

Keywords

Comments

A generalized Young tableau of shape y is an array obtained by replacing the dots in the Ferrers diagram of y with positive integers. A tableau is normal if its entries span an initial interval of positive integers.

Examples

			The a(4) = 13 tableaux:
1 1 2 2   1 1 1 1
.
1 2 2   1 1 2   1 1 1
1       2       1
.
1 2   1 1   1 1
1 2   2 2   1 1
.
1 2  1 1   1 1
1    2     1
2    2     1
.
1   1
1   1
2   1
2   1
		

Crossrefs

Programs

  • Mathematica
    undptns[y_]:=DeleteCases[Select[Tuples[Range[0,#]&/@y],OrderedQ[#,GreaterEqual]&],0,{2}];
    ehn[y_]:=ehn[y]=If[Total[y]=!=1,1,0]+Sum[ehn[c],{c,Select[undptns[y],Total[#]>1&&Total[y]-Total[#]>1&]}];
    Table[Sum[ehn[y],{y,IntegerPartitions[n]}],{n,15}]

A318915 Number of joining pairs of integer partitions of n.

Original entry on oeis.org

1, 1, 3, 5, 11, 15, 33, 41, 77, 105, 173, 215, 381, 449, 699, 911, 1335, 1611, 2433, 2867, 4179, 5113, 6903, 8251, 11769, 13661, 18177, 22011, 28997, 33711, 45251
Offset: 0

Views

Author

Gus Wiseman, Sep 05 2018

Keywords

Comments

Two integer partitions are a joining pair if they have no common cover (coarser partition) other than the maximum. For example, (221) and (311) are not a joining pair as they are both covered by (32) or (41), while (222) and (33) are a joining pair.
All terms are odd.
The same as the number of pairs of integer partitions of n without common subsums. - Mamuka Jibladze, Jun 16 2024

Examples

			The sequence of joining pairs of integer partitions begins:
  ()()   (1)(1)   (2)(2)    (3)(3)     (4)(4)      (5)(5)
                  (2)(11)   (3)(21)    (4)(31)     (5)(41)
                  (11)(2)   (3)(111)   (4)(22)     (5)(32)
                            (21)(3)    (4)(211)    (5)(311)
                            (111)(3)   (4)(1111)   (5)(221)
                                       (31)(4)     (5)(2111)
                                       (31)(22)    (5)(11111)
                                       (22)(4)     (41)(5)
                                       (22)(31)    (41)(32)
                                       (211)(4)    (32)(5)
                                       (1111)(4)   (32)(41)
                                                   (311)(5)
                                                   (221)(5)
                                                   (2111)(5)
                                                   (11111)(5)
		

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]]]];
    ptncaps[y_]:=Union[Map[Sort[Total/@#,Greater]&,mps[y],{1}]];
    Table[Select[Tuples[IntegerPartitions[n],2],Intersection@@ptncaps/@#=={{n}}&]//Length,{n,6}]

Formula

a(n) >= 2 * A000041(n) - 1. - Alois P. Heinz, Sep 06 2018

Extensions

a(13)-a(30) from Alois P. Heinz, Sep 05 2018

A300384 In the ranked poset of integer partitions ordered by refinement, number of maximal chains from the local minimum to the partition with Heinz number n.

Original entry on oeis.org

0, 1, 1, 1, 1, 1, 2, 1, 1, 1, 4, 1, 11, 2, 2, 1, 33, 1, 116, 1, 5, 4, 435, 1, 2, 11, 1, 2, 1832, 2, 8167, 1, 12, 33, 10, 1, 39700, 116, 37, 1, 201785, 5, 1099449, 4, 3, 435, 6237505, 1, 19, 2, 123, 11, 37406458, 1, 27, 2, 474, 1832, 232176847, 2, 1513796040
Offset: 1

Views

Author

Gus Wiseman, Mar 04 2018

Keywords

Comments

The Heinz number of an integer partition (y_1,...,y_k) is prime(y_1)*...*prime(y_k).

Examples

			The a(21) = 5 maximal chains are the rows:
(111111)<(21111)<(2211)<(222)<(42)
(111111)<(21111)<(2211)<(411)<(42)
(111111)<(21111)<(2211)<(321)<(42)
(111111)<(21111)<(3111)<(411)<(42)
(111111)<(21111)<(3111)<(321)<(42)
		

Crossrefs

Programs

  • Mathematica
    pcovs[ptn_]:=Select[Union[Reverse/@Sort/@Join@@@Tuples[IntegerPartitions/@ptn]],Length[#]===Length[ptn]+1&];
    coc[ptn_]:=coc[ptn]=If[Max[ptn]===1,1,Total[coc/@pcovs[ptn]]];
    primeMS[n_]:=If[n===1,{},Flatten[Cases[FactorInteger[n],{p_,k_}:>Table[PrimePi[p],{k}]]]];
    Table[coc[Reverse[primeMS[n]]],{n,50}]

A300271 Smallest Heinz number of a partition obtained from y by removing one square from its Young diagram, where y is the integer partition with Heinz number n > 1.

Original entry on oeis.org

1, 2, 2, 3, 3, 5, 4, 6, 5, 7, 6, 11, 7, 9, 8, 13, 9, 17, 10, 14, 11, 19, 12, 15, 13, 18, 14, 23, 15, 29, 16, 21, 17, 21, 18, 31, 19, 26, 20, 37, 21, 41, 22, 27, 23, 43, 24, 35, 25, 34, 26, 47, 27, 33, 28, 38, 29, 53, 30, 59, 31, 42, 32, 39, 33, 61, 34, 46
Offset: 2

Views

Author

Gus Wiseman, Mar 01 2018

Keywords

Comments

The Heinz number of an integer partition (y_1,...,y_k) is prime(y_1)*...*prime(y_k).

Crossrefs

Programs

  • Mathematica
    dip[n_]:=Min@@Table[n/q*If[q===2,1,NextPrime[q,-1]],{q,Select[Divisors[n],PrimeQ]}];
    Table[dip[n],{n,2,50}]
Previous Showing 11-16 of 16 results.