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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A325167 Heinz number of the internal portion of the integer partition with Heinz number n.

Original entry on oeis.org

1, 1, 1, 1, 1, 2, 1, 1, 2, 2, 1, 2, 1, 2, 3, 1, 1, 4, 1, 2, 3, 2, 1, 2, 3, 2, 4, 2, 1, 6, 1, 1, 3, 2, 5, 4, 1, 2, 3, 2, 1, 6, 1, 2, 6, 2, 1, 2, 5, 6, 3, 2, 1, 8, 5, 2, 3, 2, 1, 6, 1, 2, 6, 1, 5, 6, 1, 2, 3, 10, 1, 4, 1, 2, 9, 2, 7, 6, 1, 2, 8, 2, 1, 6, 5, 2, 3
Offset: 1

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Author

Gus Wiseman, Apr 05 2019

Keywords

Comments

The internal portion of an integer partition consists of all squares in the Young diagram that have a square both directly below and directly to the right.
The Heinz number of an integer partition (y_1,...,y_k) is prime(y_1)*...*prime(y_k).

Examples

			The partition with Heinz number 7865 is (6,5,5,3), with diagram
  o o o o o o
  o o o o o
  o o o o o
  o o o
with internal portion
  o o o o o
  o o o o
  o o o
which is the partition (5,4,3), with Heinz number 385, so a(7865) = 385.
		

Crossrefs

A325184 Last part of the origin-to-boundary partition of the Young diagram of the integer partition with Heinz number n.

Original entry on oeis.org

0, 1, 2, 2, 3, 1, 4, 3, 1, 1, 5, 1, 6, 1, 2, 4, 7, 2, 8, 1, 2, 1, 9, 1, 2, 1, 2, 1, 10, 1, 11, 5, 2, 1, 3, 2, 12, 1, 2, 1, 13, 1, 14, 1, 1, 1, 15, 1, 3, 1, 2, 1, 16, 3, 3, 1, 2, 1, 17, 1, 18, 1, 1, 6, 3, 1, 19, 1, 2, 1, 20, 2, 21, 1, 1, 1, 4, 1, 22, 1, 3, 1
Offset: 1

Views

Author

Gus Wiseman, Apr 08 2019

Keywords

Comments

The k-th part of the origin-to-boundary partition of a Young diagram is the number of squares graph-distance k from the lower-right boundary.
The Heinz number of an integer partition (y_1,...,y_k) is prime(y_1)*...*prime(y_k).

Examples

			The partition with Heinz number 7865 is (6,5,5,3), with diagram
  o o o o o o
  o o o o o
  o o o o o
  o o o
with origin-to-boundary graph-distances
  4 4 4 3 2 1
  3 3 3 2 1
  2 2 2 1 1
  1 1 1
giving the origin-to-boundary partition (7,5,4,3) with last part 3, so a(7865) = 3.
		

Crossrefs

Positions of 1's are A325185. Positions of 2's are A325186.

Programs

  • Mathematica
    primeptn[n_]:=If[n==1,{},Reverse[Flatten[Cases[FactorInteger[n],{p_,k_}:>Table[PrimePi[p],{k}]]]]];
    ptnmat[ptn_]:=PadRight[(ConstantArray[1,#]&)/@Sort[ptn,Greater],{Length[ptn],Max@@ptn}+1];
    corpos[mat_]:=ReplacePart[mat,Select[Position[mat,1],Times@@Extract[mat,{#+{1,0},#+{0,1}}]==0&]->0];
    Table[Apply[Plus,If[n==1,{},FixedPointList[corpos,ptnmat[primeptn[n]]][[-3]]],{0,1}],{n,100}]

A325199 Number of integer partitions of n such that the difference between the length of the minimal triangular partition containing and the maximal triangular partition contained in the Young diagram is 2.

Original entry on oeis.org

0, 0, 0, 2, 0, 2, 6, 3, 2, 9, 15, 12, 6, 12, 27, 38, 34, 22, 20, 43, 74, 94, 90, 67, 48, 69, 130, 194, 232, 230, 187, 132, 129, 218, 364, 497, 576, 578, 498, 367, 290, 378, 642, 977, 1264, 1435, 1448, 1290, 1000, 735, 728
Offset: 0

Views

Author

Gus Wiseman, Apr 11 2019

Keywords

Comments

The Heinz numbers of these partitions are given by A325197.

Examples

			The a(3) = 2 through a(10) = 15 partitions (empty columns not shown):
  (3)    (41)    (33)    (43)    (521)    (333)    (433)
  (111)  (2111)  (42)    (2221)  (32111)  (441)    (442)
                 (222)   (4111)           (522)    (532)
                 (411)                    (531)    (541)
                 (2211)                   (3222)   (3322)
                 (3111)                   (5211)   (3331)
                                          (32211)  (4222)
                                          (33111)  (4411)
                                          (42111)  (5221)
                                                   (5311)
                                                   (32221)
                                                   (33211)
                                                   (42211)
                                                   (43111)
                                                   (52111)
		

Crossrefs

Programs

  • Mathematica
    otb[ptn_]:=Min@@MapIndexed[#1+#2[[1]]-1&,Append[ptn,0]];
    otbmax[ptn_]:=Max@@MapIndexed[#1+#2[[1]]-1&,Append[ptn,0]];
    Table[Length[Select[IntegerPartitions[n],otbmax[#]-otb[#]==2&]],{n,0,30}]
Previous Showing 11-13 of 13 results.