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.

A219274 Number T(n,k) of standard Young tableaux for partitions of n into distinct parts with largest part k; triangle T(n,k), k>=0, k<=n<=k*(k+1)/2, read by columns.

Original entry on oeis.org

1, 1, 1, 2, 1, 3, 5, 16, 1, 4, 9, 49, 70, 168, 768, 1, 5, 14, 92, 204, 738, 3300, 7887, 15015, 48048, 292864, 1, 6, 20, 153, 405, 1815, 9460, 28743, 101673, 333905, 1946516, 4934930, 14454726, 34918884, 141892608, 1100742656, 1, 7, 27, 235, 715, 3630, 21307
Offset: 0

Views

Author

Alois P. Heinz, Nov 17 2012

Keywords

Comments

T(n,k) is defined for n,k >= 0. T(n,k) = 0 iff n k*(k+1)/2 = A000217(k). The triangle contains only the nonzero terms.

Examples

			T(3,2) = 2:
+------+  +------+
| 1  2 |  | 1  3 |
| 3 .--+  | 2 .--+
+---+     +---+
Triangle T(n,k) begins:
1;
.  1;
.     1;
.     2,  1;
.         3,   1;
.         5,   4,   1;
.        16,   9,   5,   1;
.             49,  14,   6,   1;
.             70,  92,  20,   7,  1;
.            168, 204, 153,  27,  8, 1;
.            768, 738, 405, 235, 35, 9, 1;
		

Crossrefs

Column heights are A000124(k-1) for k>0.
Column sums give: A219275.
Row sums give: A218293.
Diagonal and lower diagonals give: A000012, A000027 (for n>1), A000096(n-1) (for n>2).
Leftmost nonzero elements give A219339.
Column of leftmost nonzero element is A002024(n) for n>0.
Triangle read by rows reversed gives: A219356.
T(A000217(n),n) = A005118(n+1).

Programs

  • Maple
    h:= proc(l) local n; n:=nops(l); add(i, i=l)!/mul(mul(1+l[i]-j+
          add(`if`(l[k]>=j, 1, 0), k=i+1..n), j=1..l[i]), i=1..n)
        end:
    g:= proc(n, i, l) local s; s:=i*(i+1)/2;
          `if`(n=s, h([l[], seq(i-j, j=0..i-1)]), `if`(n>s, 0,
           g(n, i-1, l)+ `if`(i>n, 0, g(n-i, i-1, [l[], i]))))
        end:
    T:= (n, k)-> `if`(k>n, 0, g(n-k, k-1, [k])):
    seq(seq(T(n, k), n=k..k*(k+1)/2), k=0..7);
  • Mathematica
    h[l_] := Module[{n = Length[l]}, Total[l]!/Product[Product[1 + l[[i]] - j + Sum[If[l[[k]] >= j, 1, 0], {k, i + 1, n}], {j, 1, l[[i]]}], {i, 1, n}]];
    g[n_, i_, l_] := Module[{s = i(i + 1)/2}, If[n == s, h[Join[l, Table[i - j, {j, 0, i - 1}]]], If[n > s, 0, g[n, i - 1, l] + If[i > n, 0, g[n - i, i - 1, Append[l, i]]]]]];
    T[n_, k_] := If[k > n, 0, g[n - k, k - 1, {k}]];
    Table[Table[T[n, k], {n, k, k(k + 1)/2}], {k, 0, 7}] // Flatten (* Jean-François Alcover, Sep 01 2023, after Alois P. Heinz *)

Formula

T(n,k) = A219272(n,k) - A219272(n,k-1) for k>0.