A232227 Triangle read by rows: T(n,k) = number of crossing connected diagrams in a disk having n crossings and k chords.

1, 0, 8, 0, 1, 82, 0, 0, 43, 868, 0, 0, 11, 920, 9726, 0, 0, 1, 590, 15524, 113536, 0, 0, 0, 243, 15904, 243040, 1366570

Offset

1,3

Links

Table of n, a(n) for n=1..28.

V. Pilaud and J. Rué, Analytic combinatorics of chord and hyperchord diagrams with k crossings, arXiv preprint arXiv:1307.6440 [math.CO], 2013.

Example

Triangle begins:
  1;
  0, 8;
  0, 1, 82;
  0, 0, 43, 868;
  0, 0, 11, 920,  9726;
  0, 0,  1, 590, 15524, 113536;
  0, 0,  0, 243, 15904, 243040, 1366570;
  ...

Crossrefs

Cf. A232226 (row sums), A232225.

Sequence in context: A195447 A160389 A011104 * A322231 A261168 A329086

Adjacent sequences: A232224 A232225 A232226 * A232228 A232229 A232230

Keyword

nonn,tabl,more

Author

N. J. A. Sloane, Nov 22 2013

Status

approved