A361587 Triangle read by rows: T(n,k) is the number of weakly connected digraphs on n unlabeled nodes with k strongly connected components.

1, 0, 1, 0, 1, 1, 0, 5, 4, 4, 0, 83, 56, 36, 24, 0, 5048, 2406, 1101, 542, 267, 0, 1047008, 324917, 101307, 37017, 14947, 5647, 0, 705422362, 136882286, 27757789, 7134897, 2257234, 779257, 237317, 0, 1580348371788, 183851281949, 23086772643, 3922864504, 907027520, 258909828, 78691767, 20035307

Offset

0,8

Links

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

Example

Triangle begins:
  1;
  0,       1;
  0,       1,      1;
  0,       5,      4,      4;
  0,      83,     56,     36,    24;
  0,    5048,   2406,   1101,   542,   267;
  0, 1047008, 324917, 101307, 37017, 14947, 5647;
  ...

Prog

(PARI) \\ See PARI link in A350794 for program code.
{ my(A=A361587triang(6)); for(n=1, #A, print(A[n])) }

Crossrefs

Column k=1 is A035512.

Main diagonal is A101228.

Row sums are A003085.

Cf. A350794, A361582, A361588.

Sequence in context: A019102 A019179 A206568 * A361588 A304656 A354209

Adjacent sequences: A361584 A361585 A361586 * A361588 A361589 A361590

Keyword

nonn,tabl

Author

Andrew Howroyd, Mar 16 2023

Status

approved