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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A215120 Number T(n,k) of solid standard Young tableaux of n cells and height >= k; triangle T(n,k), n>=0, 0<=k<=n, read by rows.

Original entry on oeis.org

1, 1, 1, 3, 3, 1, 9, 9, 5, 1, 33, 33, 23, 7, 1, 135, 135, 109, 43, 9, 1, 633, 633, 557, 261, 69, 11, 1, 3207, 3207, 2975, 1641, 507, 101, 13, 1, 17589, 17589, 16825, 10503, 3787, 869, 139, 15, 1, 102627, 102627, 100007, 69077, 28205, 7487, 1369, 183, 17, 1
Offset: 0

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Author

Alois P. Heinz, Aug 03 2012

Keywords

Examples

			Triangle T(n,k) begins:
     1;
     1,    1;
     3,    3,    1;
     9,    9,    5,    1;
    33,   33,   23,    7,   1;
   135,  135,  109,   43,   9,   1;
   633,  633,  557,  261,  69,  11,  1;
  3207, 3207, 2975, 1641, 507, 101, 13,  1;
  ...
		

Crossrefs

Column k=0 gives: A207542.
Diagonal and lower diagonal give: A000012, A005408.
T(2n,n) gives A385413.

Programs

  • Maple
    b:= proc(n, k, l) option remember; `if`(n=0, 1,
           b(n-1, k, [l[], [1]])+ add(`if`(i=1 or nops(l[i]) `if`(k=0, `if`(n=0, 1, 0), b(n, min(n, k), [])):
    H:= (n, k)-> A(n,k) -`if`(k=0, 0, A(n, k-1)):
    T:= proc(n, k) option remember; `if`(k=n, 1, T(n, k+1)+ H(n, k)) end:
    seq(seq(T(n, k), k=0..n), n=0..10);
  • Mathematica
    b[n_, k_, L_] := b[n, k, L] = If[n == 0, 1, b[n - 1, k, Append[L, {1}]] + Sum[If[i == 1 || Length[L[[i]]] < Length[L[[i - 1]]], b[n - 1, k, ReplacePart[L, i -> Append[L[[i]], 1]]], 0] + Sum[If[L[[i, j]] < k && (i == 1 || L[[i, j]] < L[[i - 1, j]]) && (j == 1 || L[[i, j]] < L[[i, j - 1]]), b[n - 1, k, ReplacePart[L, i -> ReplacePart[L[[i]], j -> L[[i, j]] + 1]]], 0], {j, 1, Length[L[[i]]]}], {i, 1, Length[L]}]];
    A[n_, k_] := If[k == 0, If[n == 0, 1, 0], b[n, Min[n, k], {}]];
    H[n_, k_] := A[n, k] - If[k == 0, 0, A[n, k - 1]];
    T[n_, n_] = 1;
    T[n_, k_] := T[n, k] = T[n, k + 1] + H[n, k];
    Table[T[n, k], {n, 0, 10}, {k, 0, n}] // Flatten (* Jean-François Alcover, Apr 28 2022, after Alois P. Heinz *)

Formula

T(n,n) = 1, T(n,k) = T(n,k+1) + A214753(n,k) for k
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