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.

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

0,6

Links

Table of n, a(n) for n=0..44.

Example

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;
  ...

Prog

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

Crossrefs

Column k=0 is A361586.

Main diagonal is A003087.

Row sums are A000273.

The labeled version is A361592.

Cf. A350794, A361582, A361588.

Sequence in context: A075102 A209883 A326050 * A021396 A201317 A298526

Adjacent sequences: A361587 A361588 A361589 * A361591 A361592 A361593

Keyword

nonn,tabl

Author

Andrew Howroyd, Mar 16 2023

Status

approved