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.

A208058 Triangle by rows relating to the factorials, generated from A002260.

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 2, 4, 3, 1, 6, 12, 9, 4, 1, 24, 48, 36, 16, 5, 1, 120, 240, 180, 80, 25, 6, 1, 720, 1440, 1080, 480, 150, 36, 7, 1, 5040, 10080, 7560, 3360, 1050, 252, 49, 8, 1, 40320, 80640, 60480, 26880, 8400, 2016, 392, 64, 9, 1
Offset: 0

Views

Author

Gary W. Adamson, Feb 22 2012

Keywords

Comments

Row sums = A054091: (1, 2, 4, 10, 32, 130, 652,...)
Left border = the factorials, A000142 prefaced with a 1.

Examples

			First few rows of the triangle =
1;
1, 1;
1, 2, 1;
2, 4, 3, 1;
6, 12, 9, 4, 1;
24, 48, 36, 16, 5, 1;
120, 240, 180, 80, 25, 6, 1;
720, 1440, 1080, 480, 150, 36, 7, 1;
5040, 10080, 7560, 3360, 1050, 252, 49, 8, 1;
...
		

Crossrefs

Programs

  • Maple
    T:= proc(n) option remember; local M, k;
          M:= Matrix(n+1, (i, j)->
                     `if`(i=j, 1, `if`(i>j, j*(-1)^(i+j), 0)))^(-1);
          seq(M[n+1, k], k=1..n+1)
        end:
    seq(T(n), n=0..14);  # Alois P. Heinz, Feb 24 2012
  • Mathematica
    T[n_] := T[n] = Module[{M}, M = Table[If[i == j, 1, If[i>j, j*(-1)^(i+j), 0]], {i, 1, n+1}, {j, 1, n+1}] // Inverse; M[[n+1]]]; Table[T[n], {n, 0, 14}] // Flatten (* Jean-François Alcover, Mar 09 2015, after Alois P. Heinz *)

Formula

Inverse of:
1;
-1, 1;
1, -2, 1;
-1, 2, -3, 1;
1, -2, 3, -4, 1;
..., where triangle A002260 = (1; 1,2; 1,2,3;...)