This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A263191 #26 Nov 15 2015 17:37:46
%S A263191 1,1,1,1,1,2,1,0,1,1,3,2,2,2,0,2,0,1,0,0,0,0,1,1,4,3,5,4,2,4,0,5,2,0,
%T A263191 2,0,3,0,1,0,0,2,0,0,0,2,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,1,1,5,4,
%U A263191 9,6,7,6,3,10,6,4,4,0,9,5,2,0,4,4,4,0,0,4,3,1,0,2,4,0,4,0,0,0,3,0,0,2
%N A263191 Triangle read by rows: T(n>=0, 1<=k<=A000108(n)) is the number of Dyck paths of length 2n having k smaller elements in Tamari order.
%C A263191 Row sums give A000108.
%H A263191 Alois P. Heinz, <a href="/A263191/b263191.txt">Rows n = 0..10, flattened</a>
%H A263191 FindStat - Combinatorial Statistic Finder, <a href="http://www.findstat.org/StatisticsDatabase/St000032">The number of elements smaller than the given Dyck path in the Tamari Order</a>.
%H A263191 Wikipedia, <a href="https://en.wikipedia.org/wiki/Tamari_lattice">Tamari lattice</a>.
%F A263191 Sum_{k=1..A000108(n)} k * T(n,k) = A000260(n). - _Alois P. Heinz_, Nov 15 2015
%e A263191 Triangle begins:
%e A263191 1;
%e A263191 1;
%e A263191 1,1;
%e A263191 1,2,1,0,1;
%e A263191 1,3,2,2,2,0,2,0,1,0,0,0,0,1;
%e A263191 1,4,3,5,4,2,4,0,5,2,0,2,0,3,0,1,0,0,2,0,0,0,2,0,0,0,0,1,0,0,0,0,0,0,0, 0,0,0,0,0,0,1;
%e A263191 ...
%Y A263191 Cf. A000108, A000260.
%K A263191 nonn,tabf
%O A263191 0,6
%A A263191 _Christian Stump_, Oct 19 2015
%E A263191 Two terms (for rows 0 and 1) prepended by _Alois P. Heinz_, Nov 15 2015