A232227 - OEIS

A232227

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

%I #15 Feb 03 2024 17:36:00

%S 1,0,8,0,1,82,0,0,43,868,0,0,11,920,9726,0,0,1,590,15524,113536,0,0,0,

%T 243,15904,243040,1366570

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

%H V. Pilaud and J. Rué, <a href="https://arxiv.org/abs/1307.6440">Analytic combinatorics of chord and hyperchord diagrams with k crossings</a>, arXiv preprint arXiv:1307.6440 [math.CO], 2013.

%e Triangle begins:

%e 1;

%e 0, 8;

%e 0, 1, 82;

%e 0, 0, 43, 868;

%e 0, 0, 11, 920, 9726;

%e 0, 0, 1, 590, 15524, 113536;

%e 0, 0, 0, 243, 15904, 243040, 1366570;

%e ...

%Y Cf. A232226 (row sums), A232225.

%K nonn,tabl,more

%O 1,3

%A _N. J. A. Sloane_, Nov 22 2013