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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A238727 Number T(n,k) of standard Young tableaux with n cells where k is the largest value in the last row; triangle T(n,k), n>=0, 0<=k<=n, read by rows.

Original entry on oeis.org

1, 0, 1, 0, 0, 2, 0, 0, 1, 3, 0, 0, 1, 2, 7, 0, 0, 1, 3, 8, 14, 0, 0, 1, 4, 11, 19, 41, 0, 0, 1, 7, 19, 34, 64, 107, 0, 0, 1, 11, 32, 62, 119, 202, 337, 0, 0, 1, 21, 64, 131, 248, 418, 671, 1066, 0, 0, 1, 36, 124, 277, 545, 943, 1518, 2361, 3691
Offset: 0

Views

Author

Joerg Arndt and Alois P. Heinz, Mar 03 2014

Keywords

Comments

T(0,0) = 1 by convention.
Also the number of ballot sequences of length n having the last occurrence of the maximal value at position k.
T(n,3) = A051920(n-3) for n>3.
T(2*n,n) gives A246818.
Main diagonal gives A238728.
Row sums give A000085.

Examples

			The 10 tableaux with n=4 cells sorted by largest value in the last row:
  :[1 3 4]:[1 4] [1 2 4]:[1] [1 2] [1 3] [1 2 3] [1 2] [1 3] [1 2 3 4]:
  :[2]    :[2]   [3]    :[2] [3]   [2]   [4]     [3 4] [2 4]          :
  :       :[3]          :[3] [4]   [4]                                :
  :       :             :[4]                                          :
  : --2-- : -----3----- : ---------------------4--------------------- :
The 10 ballot sequences of length 4 sorted by the position of the last occurrence of the maximal value:
  [1, 2, 1, 1]  ->  2 } -- 1
  [1, 2, 3, 1]  ->  3 \ __ 2
  [1, 1, 2, 1]  ->  3 /
  [1, 2, 3, 4]  ->  4 \
  [1, 1, 2, 3]  ->  4  \
  [1, 2, 1, 3]  ->  4   \
  [1, 1, 1, 2]  ->  4    } 7
  [1, 1, 2, 2]  ->  4   /
  [1, 2, 1, 2]  ->  4  /
  [1, 1, 1, 1]  ->  4 /
thus row 4 = [0, 0, 1, 2, 7].
Triangle T(n,k) begins:
  00:   1;
  01:   0, 1;
  02:   0, 0, 2;
  03:   0, 0, 1,  3;
  04:   0, 0, 1,  2,   7;
  05:   0, 0, 1,  3,   8,  14;
  06:   0, 0, 1,  4,  11,  19,  41;
  07:   0, 0, 1,  7,  19,  34,  64, 107;
  08:   0, 0, 1, 11,  32,  62, 119, 202,  337;
  09:   0, 0, 1, 21,  64, 131, 248, 418,  671, 1066;
  10:   0, 0, 1, 36, 124, 277, 545, 943, 1518, 2361, 3691;
		

Programs

  • Maple
    h:= proc(l) option remember; local n, s; n:= nops(l); s:= add(i, i=l);
         `if`(n=0, 1, add(`if`(il[i+1], h(subsop(i=l[i]-1, l)),
         `if`(i=n, (p->add(coeff(p,x,j)*x^`if`(j1, l[i]-1, [][]), l))), 0)), i=1..n))
        end:
    g:= (n, i, l)-> `if`(n=0 or i=1, h([l[], 1$n]),
           add(g(n-i*j, i-1, [l[], i$j]), j=0..n/i)):
    T:= n-> (p->seq(coeff(p, x, i), i=0..n))(g(n$2, [])):
    seq(T(n), n=0..12);
  • Mathematica
    h[l_] := h[l] = With[{n = Length[l], s = Total[l]},
         If[n == 0, 1, Sum[If[i < n && l[[i]] > l[[i + 1]],
         h[ReplacePart[l, i -> l[[i]] - 1]], If[i == n, Function[p,
         Sum[Coefficient[p, x, j] x^If[j < s, s, j], {j, 0,
         Exponent[p, x]}]][h[ReplacePart[l, i -> If[l[[i]] > 1,
         l[[i]] - 1, Nothing]]]], 0]], {i, n}]]];
    g[n_, i_, l_] := If[n == 0 || i == 1, h[Join[l, Table[1, {n}]]],
         Sum[g[n - i*j, i - 1, Join[l, Table[i, {j}]]], {j, 0, n/i}]];
    T[n_] := CoefficientList[g[n, n, {}], x];
    Table[T[n], {n, 0, 10}] // Flatten (* Jean-François Alcover, Aug 27 2021, after Maple code *)

A369589 Triangular array read by rows: T(m,n) = number of Yamanouchi words over the alphabet {1, 2, ..., n} of length m that start with n, m >= 1, n = 1..m.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 3, 2, 1, 1, 4, 5, 3, 1, 1, 10, 14, 11, 4, 1, 1, 15, 35, 31, 19, 5, 1, 1, 35, 90, 106, 69, 29, 6, 1, 1, 56, 245, 323, 265, 127, 41, 7, 1, 1, 126, 644, 1093, 971, 583, 209, 55, 8, 1, 1, 210, 1716, 3439, 3644, 2446, 1106, 319, 71, 9, 1, 1, 462, 4707, 11716, 13771, 10616, 5323, 1904, 461, 89, 10, 1
Offset: 1

Views

Author

Max Alekseyev, Jan 26 2024

Keywords

Examples

			Array starts with
  m=1: 1
  m=2: 1,  1
  m=3: 1,  1,  1
  m=4: 1,  3,  2,  1
  m=5: 1,  4,  5,  3,  1
  m=6: 1, 10, 14, 11,  4, 1
  m=7: 1, 15, 35, 31, 19, 5, 1
		

Crossrefs

Row sums: A238728.
Columns: A000012 (n=1), A037952 (n=2), A369591 (n=3).

A369591 a(n) = number of Yamanouchi words over the alphabet {1, 2, 3} of length n that start with 3.

Original entry on oeis.org

0, 0, 1, 2, 5, 14, 35, 90, 245, 644, 1716, 4707, 12727, 34683, 96174, 264784, 732785, 2051338, 5719684, 16007081, 45160093, 127106181, 358743903, 1018566177, 2887666445, 8204375034
Offset: 1

Views

Author

Max Alekseyev, Jan 26 2024

Keywords

Crossrefs

Column 3 in A369589.
Number of Yamanouchi words over the alphabet {1, 2, 3} is given by A001006, and by A217323 for the words containing 3.
Showing 1-3 of 3 results.