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.

A357079 Triangle read by rows. T(n, k) = A356265(n, k) + A357078(n, k) for 0 <= k <= n.

Original entry on oeis.org

1, 0, 1, 0, 1, 1, 0, 3, 2, 1, 0, 9, 12, 2, 1, 0, 49, 37, 31, 2, 1, 0, 329, 149, 176, 63, 2, 1, 0, 2561, 794, 853, 702, 127, 2, 1, 0, 22369, 5599, 3836, 5709, 2549, 255, 2, 1, 0, 216225, 47275, 18422, 37609, 33949, 8886, 511, 2, 1, 2291457, 451176, 107535, 218506, 344670, 184653, 29777, 1023, 2, 1
Offset: 0

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Author

Peter Luschny, Sep 11 2022

Keywords

Comments

The triangle is the termwise sum of a refinement of the number of irreducible permutations A357078, and A356265, which is a refinement of the number of reducible permutations.

Examples

			Triangle T(n, k) starts:                                 [Row sums]
[0] 1;                                                       [1]
[1] 0,     1;                                                [1]
[2] 0,     1,      1;                                        [2]
[3] 0,     3,      2,     1;                                 [6]
[4] 0,     9,     12,     2,     1;                          [24]
[5] 0,    49,     37,    31,     2,     1;                   [120]
[6] 0,   329,    149,   176,    63,     2,    1;             [720]
[7] 0,   2561,   794,   853,   702,   127,    2,   1;        [5040]
[8] 0,  22369,  5599,  3836,  5709,  2549,  255,   2, 1;     [40320]
[9] 0, 216225, 47275, 18422, 37609, 33949, 8886, 511, 2, 1;  [362880]
		

Crossrefs

Programs

  • SageMath
    def A357079_triangle(dim):
        T = A357078_triangle(dim)
        return [[0^n] + [T[n][k+1] + A356265_row(n)[k]
               for k in range(n)] for n in range(dim)]
    A357079_triangle(9)