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.

A226167 Array read by antidiagonals: a(i,j) is the number of ways of labeling a tableau of shape (i,1^j) with the integers 1, 2, ... i+j-2 (each label being used once) such that the first row is decreasing, and the first column has m-1 labels.

Original entry on oeis.org

1, 3, 1, 12, 5, 1, 60, 27, 7, 1, 360, 168, 48, 9, 1, 2520, 1200, 360, 75, 11, 1, 20160, 9720, 3000, 660, 108, 13, 1, 181440, 88200, 27720, 6300, 1092, 147, 15, 1, 1814400, 887040, 282240, 65520, 11760, 1680, 192, 17, 1, 19958400, 9797760, 3144960, 740880, 136080, 20160, 2448, 243, 19, 1
Offset: 1

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Author

John M. Campbell, May 29 2013

Keywords

Comments

For an arbitrary composition c, let F_c^p denote the linear transformation of NSym that is adjoint to multiplication by the fundamental quasi-symmetric function indexed by c. Then a(i,j) equals the coefficient of H_(1,1) in (F_(1)^p)^(i+j-2)(H_(i,1^j)) (see below SAGE program, and Corollary 2.7 in the below link).
Let M(n) = [a(i,j)]_{n x n}. Then det(M(n))=A000178(n)=the n-th superfactorial.
Let p_n(x) denote the polynomial such that a(x,n)=p_n(x). Then the coefficient of x in p_n(x) is |A009575(n)|. For example, p_4(x)=4x^3+18x^2+26x+12, and the coefficient of x in p_4(x) is |A009575(4)|=26.
First row is A001710. Second row is A138772. Fourth row is A136659.

Examples

			There are a(3,2) = 7 ways of labeling the tableau of shape (3,1,1) with 1, 2 and 3 (with each label being used once) such that the first row is decreasing and the first column has 1 label:
1    2    3    X    X    X    X
X    X    X    1    2    3    X
X32  X31  X21  X32  X31  X21  321
The matrix [a(i,j)]_(6 x 6) is given below:
[1  3  12   60   360   2520]
[1  5  27  168  1200   9720]
[1  7  48  360  3000  27720]
[1  9  75  660  6300  65520]
[1 11 108 1092 11760 136080]
[1 13 147 1680 20160 257040]
		

Crossrefs

Main diagonal gives: A023999. - Alois P. Heinz, Jan 21 2014

Programs

  • Maple
    a:= (i, j)-> (i+j-2)!/i!*(2*i+j-1)*j/2:
    seq(seq(a(i, 1+d-i), i=1..d), d=1..12);  # Alois P. Heinz, Jan 21 2014
  • Mathematica
    a[n_,k_]:=(n+k-2)!/n!*(2*n+k-1)*k/2 ;
    Print[Array[a[#1,#2]&,{50,50}]//MatrixForm]
    (* A program which gives a list of tableaux *)
    a[i_, j_] :=  Module[{f, list1, el, emptylist, n},
      f[q_] := StringReplace[StringReplace[StringReplace[    StringReplace[ToString[q], ToString[i + j - 1] -> "X"], ", " -> ""], "{" -> ""], "}" -> ""]; list1 = Permutations[Join[Table[q, {q, 1, i + j - 2}], {i + j - 1, i + j - 1}]]; el[q_] := First[Take[list1, {q, q}]]; emptylist = {}; n = 1; While[n < 1 + Length[list1], If[Take[el[n], {j + 1, i + j}] == Sort[Take[el[n], {j + 1, i + j}], Greater] && Count[Take[el[n], {1, j + 1}], i + j - 1] == 2, emptylist = Append[emptylist, f[el[n]]], Null]; n++]; Print[emptylist]]
  • Sage
    NSym = NonCommutativeSymmetricFunctions(QQ) ;
    QSym = QuasiSymmetricFunctions(QQ) ;
    F = QSym.Fundamental() ;
    H = NSym.complete() ;
    def a(n, m):
         expr = H([n]+[1 for q in range(m)]) ;
         w=1 ;
         while w
    				

Formula

a(i,j) = (i+j-2)!/i!*(2*i+j-1)*j/2.