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.

A324362 Total number of occurrences of k in the (signed) displacement sets of all permutations of [n+k] divided by k!; square array A(n,k), n>=0, k>=0, read by antidiagonals.

Original entry on oeis.org

0, 0, 1, 0, 1, 1, 0, 1, 3, 4, 0, 1, 5, 13, 15, 0, 1, 7, 28, 67, 76, 0, 1, 9, 49, 179, 411, 455, 0, 1, 11, 76, 375, 1306, 2921, 3186, 0, 1, 13, 109, 679, 3181, 10757, 23633, 25487, 0, 1, 15, 148, 1115, 6576, 29843, 98932, 214551, 229384, 0, 1, 17, 193, 1707, 12151, 69299, 307833, 1006007, 2160343, 2293839
Offset: 0

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Author

Alois P. Heinz, Feb 23 2019

Keywords

Examples

			Square array A(n,k) begins:
    0,    0,     0,     0,     0,      0,      0, ...
    1,    1,     1,     1,     1,      1,      1, ...
    1,    3,     5,     7,     9,     11,     13, ...
    4,   13,    28,    49,    76,    109,    148, ...
   15,   67,   179,   375,   679,   1115,   1707, ...
   76,  411,  1306,  3181,  6576,  12151,  20686, ...
  455, 2921, 10757, 29843, 69299, 142205, 266321, ...
		

Crossrefs

Rows n=0-3 give: A000004, A000012, A005408, A056107(k+1).
Main diagonal gives A324361.
Cf. A306234.

Programs

  • Maple
    A:= (n, k)-> -add((-1)^j*binomial(n, j)*(n+k-j)!, j=1..n)/k!:
    seq(seq(A(n, d-n), n=0..d), d=0..12);
  • Mathematica
    m = 10;
    col[k_] := col[k] = CoefficientList[(1-Exp[-x])/(1-x)^(k+1)+O[x]^(m+1), x]* Range[0, m]!;
    A[n_, k_] := col[k][[n+1]];
    Table[A[n, d-n], {d, 0, m}, {n, 0, d}] // Flatten (* Jean-François Alcover, May 03 2021 *)

Formula

E.g.f. of column k: (1-exp(-x))/(1-x)^(k+1).
A(n,k) = -1/k! * Sum_{j=1..n} (-1)^j * binomial(n,j) * (n+k-j)!.
A(n,k) = A306234(n+k,k).