A361582 Triangle read by rows: T(n,k) is the number of digraphs on n unlabeled nodes with k strongly connected components.

1, 0, 1, 0, 1, 2, 0, 5, 5, 6, 0, 83, 62, 42, 31, 0, 5048, 2494, 1172, 592, 302, 0, 1047008, 330063, 103961, 38312, 15616, 5984, 0, 705422362, 137934757, 28095923, 7243110, 2297690, 795930, 243668, 0, 1580348371788, 184557780045, 23226116293, 3951426731, 914429926, 261269562, 79512478, 20286025

Offset

0,6

Links

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

Wikipedia, Strongly connected component.

Example

Triangle begins:
  1;
  0,       1;
  0,       1,      2;
  0,       5,      5,      6;
  0,      83,     62,     42,    31;
  0,    5048,   2494,   1172,   592,   302;
  0, 1047008, 330063, 103961, 38312, 15616, 5984;
  ...

Prog

(PARI) \\ See PARI link in A350794 for program code.
{ my(A=A361582triang(6)); for(n=1, #A, print(A[n])) }

Crossrefs

Column k=1 is A035512.

Main diagonal is A003087.

Row sums are A000273.

The labeled version is A361455.

Cf. A106238, A350794, A361587, A361588.

Sequence in context: A197253 A249693 A251420 * A137421 A155524 A051111

Adjacent sequences: A361579 A361580 A361581 * A361583 A361584 A361585

Keyword

nonn,tabl

Author

Andrew Howroyd, Mar 16 2023

Status

approved