|
%I #16 Jan 01 2021 15:35:39
%S 1,2,11,5,10,154,540,581,272,49,122,3418,27304,90277,150948,150519,
%T 95088,37797,8714,893,3346,142760,1938178,12186976,42696630,94605036,
%U 145009210,161845163,134933733,84656743,39632149,13481441,3156845,455917,30649
%N Irregular triangle read by rows: T(n,k) (n>=2, k>=1) is the number of strong digraphs on n nodes with k descents.
%H Kassie Archer, Ira M. Gessel, Christina Graves, and Xuming Liang, <a href="https://arxiv.org/abs/1909.01550">Counting acyclic and strong digraphs by descents</a>, arXiv:1909.01550 [math.CO], 20 Mar 2020.
%e Triangle begins:
%e 1;
%e 2, 11, 5;
%e 10, 154, 540, 581, 272, 49;
%e 122, 3418, 27304, 90277, 150948, 150519, 95088, 37797, 8714, 893;
%e 3346, 142760, 1938178, 12186976, 42696630, 94605036, 145009210, 161845163, 134933733, 84656743, 39632149, 13481441, 3156845, 455917, 30649;
%e ...
%Y Cf. A003030 (row sums), A057273 (another version of the same triangle), A307049, A339590.
%K nonn,tabf
%O 2,2
%A _Hugo Pfoertner_, Dec 28 2020
%E Row 2 added by _N. J. A. Sloane_, Dec 29 2020
|
