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.

A215122 Number T(n,k) of solid standard Young tableaux of shape [[(n-k)*k,k],[n-k]]; triangle T(n,k), n>=0, 0<=k<=n, read by rows.

Original entry on oeis.org

1, 0, 0, 0, 2, 0, 0, 8, 8, 0, 0, 30, 174, 30, 0, 0, 112, 2084, 2084, 112, 0, 0, 420, 21025, 52808, 21025, 420, 0, 0, 1584, 194064, 994788, 994788, 194064, 1584, 0, 0, 6006, 1694224, 16074586, 31497284, 16074586, 1694224, 6006, 0
Offset: 0

Views

Author

Alois P. Heinz, Aug 03 2012

Keywords

Examples

			Triangle T(n,k) begins:
  1;
  0,    0;
  0,    2,      0;
  0,    8,      8,      0;
  0,   30,    174,     30,      0;
  0,  112,   2084,   2084,    112,      0;
  0,  420,  21025,  52808,  21025,    420,    0;
  0, 1584, 194064, 994788, 994788, 194064, 1584,  0;
		

Crossrefs

Columns k=0-2 give: A000007, A162551(n-1), A215124.
Central elements of rows give A215123.

Programs

  • Maple
    b:= proc(x, y, z) option remember; `if`(zy and x>z, b(x-1, y, z), 0)+
          `if`(y>0, b(x, y-1, z), 0)+ `if`(z>0, b(x, y, z-1), 0)))
        end:
    T:= (n, k)-> `if`(k=0 xor k=n, 0, b((n-k)*k, k, n-k)):
    seq(seq(T(n, k), k=0..n), n=0..10);
  • Mathematica
    b[x_, y_, z_] := b[x, y, z] = If[zy && x>z, b[x-1, y, z], 0] + If[y>0, b[x, y-1, z], 0] + If[z>0, b[x, y, z-1], 0]]]; T[n_, k_] := If[k == 0 || k == n, 0, b[(n-k)*k, k, n-k]]; T[0, 0] = 1; Table[Table[T[n, k], {k, 0, n}], {n, 0, 10}] // Flatten (* Jean-François Alcover, Jan 19 2015, after Alois P. Heinz *)