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.

A361590 Triangle read by rows: T(n,k) is the number of digraphs on n unlabeled nodes with exactly k strongly connected components of size 1.

Original entry on oeis.org

1, 0, 1, 1, 0, 2, 5, 5, 0, 6, 90, 55, 42, 0, 31, 5289, 2451, 974, 592, 0, 302, 1071691, 323709, 94332, 29612, 15616, 0, 5984, 712342075, 135208025, 25734232, 6059018, 1650492, 795930, 0, 243668, 1585944117738, 181427072519, 21650983294, 3358042412, 704602272, 174576110, 79512478, 0, 20286025
Offset: 0

Views

Author

Andrew Howroyd, Mar 16 2023

Keywords

Examples

			Triangle begins:
        1;
        0,      1;
        1,      0,     2;
        5,      5,     0,     6;
       90,     55,    42,     0,    31;
     5289,   2451,   974,   592,     0, 302;
  1071691, 323709, 94332, 29612, 15616,   0, 5984;
  ...
		

Crossrefs

Column k=0 is A361586.
Main diagonal is A003087.
Row sums are A000273.
The labeled version is A361592.

Programs

  • PARI
    \\ See PARI link in A350794 for program code.
    { my(A=A361590triang(6)); for(n=1, #A, print(A[n])) }