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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A214722 Number A(n,k) of solid standard Young tableaux of shape [[{n}^k],[n]]; square array A(n,k), n>=0, k>=1, read by antidiagonals.

Original entry on oeis.org

1, 1, 1, 1, 2, 2, 1, 3, 16, 5, 1, 4, 91, 192, 14, 1, 5, 456, 5471, 2816, 42, 1, 6, 2145, 143164, 464836, 46592, 132, 1, 7, 9724, 3636776, 75965484, 48767805, 835584, 429, 1, 8, 43043, 91442364, 12753712037, 55824699632, 5900575762, 15876096, 1430
Offset: 0

Views

Author

Alois P. Heinz, Jul 26 2012

Keywords

Examples

			Square array A(n,k) begins:
   1,     1,        1,           1,              1,                 1, ...
   1,     2,        3,           4,              5,                 6, ...
   2,    16,       91,         456,           2145,              9724, ...
   5,   192,     5471,      143164,        3636776,          91442364, ...
  14,  2816,   464836,    75965484,    12753712037,     2214110119572, ...
  42, 46592, 48767805, 55824699632, 70692556053053, 98002078234748974, ...
		

Crossrefs

Columns k=1-4 give: A000108, A006335, A213978, A215220.
Rows n=0-3 give: A000012, A000027, A214824, A211505.
A(n,n) gives A258583.

Programs

  • Maple
    b:= proc(l) option remember; local m; m:= nops(l);
          `if`({map(x-> x[], l)[]}={0}, 1, add(add(`if`(l[i][j]>
          `if`(i=m or nops(l[i+1])
          `if`(nops(l[i])=j, 0, l[i][j+1]), b(subsop(i=subsop(
           j=l[i][j]-1, l[i]), l)), 0), j=1..nops(l[i])), i=1..m))
        end:
    A:= (n, k)-> b([[n$k], [n]]):
    seq(seq(A(n, 1+d-n), n=0..d), d=0..10);
  • Mathematica
    b[l_List] := b[l] = With[{m = Length[l]}, If[Union[Flatten[l]] == {0}, 1, Sum[Sum[If[l[[i, j]] > If[i == m || Length[l[[i+1]]] < j, 0, l[[i+1, j]]] && l[[i, j]] > If[Length[l[[i]]] == j, 0, l[[i, j+1]]], b[ReplacePart[l, i -> ReplacePart[l[[i]], j -> l[[i, j]] - 1]]], 0], {j, 1, Length[l[[i]]]}], {i, 1, m}]] ]; a[n_, k_] := b[{Array[n&, k], {n}}]; Table[Table[a[n, 1+d-n], {n, 0, d}], {d, 0, 10}] // Flatten (* Jean-François Alcover, Dec 17 2013, translated from Maple *)

A259101 Square array read by antidiagonals arising in the enumeration of corners.

Original entry on oeis.org

1, 2, 2, 5, 16, 5, 14, 91, 91, 14, 42, 456, 936, 456, 42, 132, 2145, 7425, 7425, 2145, 132, 429, 9724, 50765, 85800, 50765, 9724, 429, 1430, 43043, 315315, 805805, 805805, 315315, 43043, 1430, 4862, 187408, 1831648, 6584032, 9962680, 6584032, 1831648, 187408, 4862, 16796, 806208, 10127988, 48674808, 103698504, 103698504, 48674808, 10127988, 806208, 16796
Offset: 0

Views

Author

N. J. A. Sloane, Jun 22 2015

Keywords

Comments

See Kreweras (1979) for precise definition.

Examples

			The first few antidiagonals are:
    1,
    2,    2,
    5,   16,    5,
   14,   91,   91,   14,
   42,  456,  936,  456,   42,
  132, 2145, 7425, 7425, 2145, 132,
  ...
		

Crossrefs

The first row and column of the array are the Catalan numbers A000108.
The second row and column are A214824.

Programs

  • Mathematica
    a[x_, y_] := (2(2x+2y+1)!(x^2+3x*y+y^2+4x+4y+3)) / (x!(x+1)!y!(y+1)!(x+y+1)(x+y+2)(x+y+3));
    Table[Table[a[x-y, y], {y, 0, x}] // Reverse, {x, 0, 9}] // Flatten (* Jean-François Alcover, Aug 11 2017 *)

Formula

Kreweras gives an explicit formula for the general term (see bottom display on page 291).

Extensions

More terms from Jean-François Alcover, Aug 11 2017
Showing 1-2 of 2 results.