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 21-23 of 23 results.

A369910 Number of pairs (p,q) of partitions of n such that the set of parts in q is a proper subset of the set of parts in p.

Original entry on oeis.org

0, 0, 0, 1, 3, 4, 15, 20, 52, 83, 163, 246, 501, 727, 1295, 1994, 3375, 4969, 8267, 12036, 19287, 28270, 43511, 62799, 96364, 137358, 204388, 291607, 427446, 601257, 874088, 1218524, 1743989, 2424096, 3422084, 4718626, 6622937, 9053800, 12559895, 17112883
Offset: 0

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Author

Alois P. Heinz, Feb 05 2024

Keywords

Examples

			a(5) = 4: (2111, 11111), (221, 11111), (311, 11111), (41, 11111).
a(6) = 15: (21111, 111111), (21111, 222), (2211, 111111), (2211, 222), (3111, 111111), (321, 111111), (321, 21111), (321, 2211), (321, 222), (321, 3111), (3111, 33), (321, 33), (411, 111111), (42, 222), (51, 111111).
		

Crossrefs

Programs

  • Maple
    b:= proc(n, m, i, t) option remember; `if`(n=0,
         `if`(t and m=0, 1, 0), `if`(i<1, 0, b(n, m, i-1, t)+add(
          add(b(n-i*j, m-i*h, i-1, h=0 or t), h=0..m/i), j=1..n/i)))
        end:
    a:= n-> b(n$3, false):
    seq(a(n), n=0..42);
  • Mathematica
    b[n_, m_, i_, t_] := b[n, m, i, t] = If[n == 0,
       If[t && m == 0, 1, 0], If[i < 1, 0, b[n, m, i-1, t] +
       Sum[Sum[b[n-i*j, m-i*h, i-1, h == 0 || t], {h, 0, m/i}], {j, 1, n/i}]]];
    a[n_] := b[n, n, n, False];
    Table[a[n], {n, 0, 42}] (* Jean-François Alcover, Feb 29 2024, after Alois P. Heinz *)

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

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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}]

A305023 Number of triples (p,q,r) of partitions such that p is a partition of n and r <= q <= p (by diagram containment).

Original entry on oeis.org

1, 3, 12, 34, 100, 246, 630, 1433, 3298, 7124, 15283, 31358, 64100, 126406, 247587, 472864, 895548, 1661690, 3059734, 5538991, 9950980, 17631398, 31004004, 53878023, 92979904, 158806852, 269448833, 453099946, 757152246, 1255180557, 2068707378, 3385065586
Offset: 0

Views

Author

Alois P. Heinz, May 23 2018

Keywords

Examples

			a(0) = 1: ((),(),()).
a(1) = 3: (1,(),()), (1,1,()), (1,1,1).
a(2) = 12: (11,(),()), (11,1,()), (11,1,1), (11,11,()), (11,11,1), (11,11,11), (2,(),()), (2,1,()), (2,1,1), (2,2,()), (2,2,1), (2,2,2).
a(3) = 34: (111,(),()), (111,1,()), (111,1,1), (111,11,()), (111,11,1), (111,11,11), (111,111,()), (111,111,1), (111,111,11), (111,111,111), (21,(),()), (21,1,()), (21,1,1), (21,11,()), (21,11,1), (21,11,11), (21,2,()), (21,2,1), (21,2,2), (21,21,()), (21,21,1), (21,21,11), (21,21,2), (21,21,21), (3,(),()), (3,1,()), (3,1,1), (3,2,()), (3,2,1), (3,2,2), (3,3,()), (3,3,1), (3,3,2), (3,3,3).
		

Crossrefs

Previous Showing 21-23 of 23 results.