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.

Showing 1-5 of 5 results.

A325187 Number of integer partitions of n such that the upper-left square of the Young diagram has strictly greater graph-distance from the lower-right boundary than any other square.

Original entry on oeis.org

1, 0, 1, 3, 3, 5, 9, 14, 20, 26, 38, 53, 75, 101, 132, 175, 229, 301, 394, 509, 650, 826, 1043, 1315, 1656, 2074, 2590, 3218, 3975, 4896, 6008, 7361, 8989, 10960, 13323, 16159, 19531, 23553, 28323, 34002, 40723, 48694, 58115, 69249, 82350, 97766, 115832
Offset: 1

Views

Author

Gus Wiseman, Apr 11 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 sequence gives the number of integer partitions of n whose Young diagram has last part of its origin-to-boundary partition equal to 1.
The Heinz numbers of these partitions are given by A325185.

Examples

			The a(1) = 1 through a(8) = 14 partitions:
  (1)  (21)  (22)   (41)    (51)     (61)      (71)
             (31)   (311)   (321)    (322)     (332)
             (211)  (2111)  (411)    (331)     (422)
                            (3111)   (421)     (431)
                            (21111)  (511)     (521)
                                     (3211)    (611)
                                     (4111)    (3221)
                                     (31111)   (3311)
                                     (211111)  (4211)
                                               (5111)
                                               (32111)
                                               (41111)
                                               (311111)
                                               (2111111)
		

Crossrefs

Programs

  • Mathematica
    otb[ptn_]:=Min@@MapIndexed[#1+#2[[1]]-1&,Append[ptn,0]];
    Table[Length[Select[IntegerPartitions[n],otb[#]>otb[Rest[#]]&&otb[#]>otb[DeleteCases[#-1,0]]&]],{n,30}]

A325183 Heinz number of the origin-to-boundary partition of the Young diagram of the integer partition with Heinz number n.

Original entry on oeis.org

1, 2, 3, 3, 5, 6, 7, 5, 10, 10, 11, 10, 13, 14, 15, 7, 17, 15, 19, 14, 21, 22, 23, 14, 21, 26, 21, 22, 29, 30, 31, 11, 33, 34, 35, 21, 37, 38, 39, 22, 41, 42, 43, 26, 42, 46, 47, 22, 55, 42, 51, 34, 53, 35, 55, 26, 57, 58, 59, 42, 61, 62, 66, 13, 65, 66, 67
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 Heinz number 6545, so a(7865) = 6545.
		

Crossrefs

The only terms appearing only once are the primorials A002110.
The union consists of all squarefree numbers A005117.

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[Times@@Prime/@If[n==1,{},-Differences[Map[Total,Drop[FixedPointList[corpos,ptnmat[primeptn[n]]],-1],2]]],{n,30}]

A325185 Heinz numbers of integer partitions such that the upper-left square of the Young diagram has strictly greater graph-distance from the lower-right boundary than any other square.

Original entry on oeis.org

2, 6, 9, 10, 12, 14, 20, 22, 24, 26, 28, 30, 34, 38, 40, 42, 44, 45, 46, 48, 50, 52, 56, 58, 60, 62, 63, 66, 68, 70, 74, 75, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 99, 100, 102, 104, 106, 110, 112, 114, 116, 117, 118, 120, 122, 124, 125, 126, 130, 132
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 sequence gives all Heinz numbers of integer partitions whose Young diagram has last part of its origin-to-boundary partition equal to 1.
The Heinz number of an integer partition (y_1,...,y_k) is prime(y_1)*...*prime(y_k).

Examples

			The sequence of terms together with their prime indices begins:
    2: {1}
    6: {1,2}
    9: {2,2}
   10: {1,3}
   12: {1,1,2}
   14: {1,4}
   20: {1,1,3}
   22: {1,5}
   24: {1,1,1,2}
   26: {1,6}
   28: {1,1,4}
   30: {1,2,3}
   34: {1,7}
   38: {1,8}
   40: {1,1,1,3}
   42: {1,2,4}
   44: {1,1,5}
   45: {2,2,3}
   46: {1,9}
   48: {1,1,1,1,2}
		

Crossrefs

Programs

  • Mathematica
    hptn[n_]:=If[n==1,{},Reverse[Flatten[Cases[FactorInteger[n],{p_,k_}:>Table[PrimePi[p],{k}]]]]];
    otb[ptn_]:=Min@@MapIndexed[#1+#2[[1]]-1&,Append[ptn,0]];
    Select[Range[2,100],otb[hptn[#]]>otb[Rest[hptn[#]]]&&otb[hptn[#]]>otb[DeleteCases[hptn[#]-1,0]]&]

A325186 Heinz numbers of integer partitions whose Young diagram has last part of its origin-to-boundary partition equal to 2.

Original entry on oeis.org

3, 4, 15, 18, 21, 25, 27, 33, 36, 39, 51, 57, 69, 72, 87, 93, 105, 111, 123, 129, 141, 144, 147, 150, 159, 165, 175, 177, 183, 195, 201, 213, 219, 225, 231, 237, 245, 249, 250, 255, 267, 273, 275, 285, 288, 291, 300, 303, 309, 321, 325, 327, 339, 343, 345, 357
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 sequence of terms together with their prime indices begins:
    3: {2}
    4: {1,1}
   15: {2,3}
   18: {1,2,2}
   21: {2,4}
   25: {3,3}
   27: {2,2,2}
   33: {2,5}
   36: {1,1,2,2}
   39: {2,6}
   51: {2,7}
   57: {2,8}
   69: {2,9}
   72: {1,1,1,2,2}
   87: {2,10}
   93: {2,11}
  105: {2,3,4}
  111: {2,12}
  123: {2,13}
  129: {2,14}
		

Crossrefs

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];
    Select[Range[100],Apply[Plus,If[#==1,{},FixedPointList[corpos,ptnmat[primeptn[#]]][[-3]]],{0,1}]==2&]

A325190 Number of integer partitions of n whose Young diagram has last part of its origin-to-boundary partition equal to 2.

Original entry on oeis.org

0, 0, 2, 0, 0, 2, 4, 2, 2, 4, 8, 10, 12, 10, 14, 20, 28, 36, 44, 46, 56, 66, 86, 108, 136, 160, 190, 214, 252, 298, 364, 434, 524, 620, 728, 834, 966, 1112, 1306, 1522, 1788, 2088, 2448, 2822, 3256, 3720, 4264, 4876, 5610, 6434, 7420
Offset: 0

Views

Author

Gus Wiseman, Apr 11 2019

Keywords

Comments

The Heinz numbers of these partitions are given by A325186.
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. For example, the partition (6,5,5,3) has 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).

Examples

			The a(2) = 1 through a(11) = 10 partitions:
  (2)   (32)   (33)    (52)     (62)      (72)       (82)        (92)
  (11)  (221)  (42)    (22111)  (221111)  (432)      (433)       (443)
               (222)                      (3321)     (442)       (533)
               (2211)                     (2211111)  (532)       (542)
                                                     (3322)      (632)
                                                     (3331)      (3332)
                                                     (33211)     (33221)
                                                     (22111111)  (33311)
                                                                 (332111)
                                                                 (221111111)
		

Crossrefs

Programs

  • Mathematica
    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[Length[Select[IntegerPartitions[n],Apply[Plus,If[#=={},{},FixedPointList[corpos,ptnmat[#]][[-3]]],{0,1}]==2&]],{n,30}]
Showing 1-5 of 5 results.