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 A140714 #6 Nov 28 2018 12:20:14
%S A140714 1,3,1,9,5,2,28,19,12,5,90,68,51,33,14,297,240,197,150,98,42,1001,847,
%T A140714 735,609,466,306,132
%N A140714 Triangle read by rows: T(n,k) is the number of white corners of rank k in all 321-avoiding permutations of {1,2,...,n} (n>=2, 0<=k<=n-2; for definitions see the Eriksson-Linusson references).
%C A140714 Sum of entries in row n is 4^(n-2) (A000302).
%C A140714 T(n,0)=A000245(n-1).
%C A140714 T(n,n-2)=Cat(n-2)=A000108(n-2).
%D A140714 K. Eriksson and S. Linusson. Combinatorics of Fulton's essential set. Duke Mathematical Journal 85(1):61-76, 1996.
%H A140714 K. Eriksson and S. Linusson, <a href="http://www.combinatorics.org/ojs/index.php/eljc/article/view/v2i1r6">The size of Fulton's essential set</a>, Electronic J. Combinatorics, Vol. 2, #R6, 1995.
%H A140714 K. Eriksson and S. Linusson, <a href="https://www.researchgate.net/publication/2550835_Combinatorics_of_Fulton's_essential_set">Combinatorics of Fulton's essential set</a>, ResearchGate, 1998.
%e A140714 Triangle starts:
%e A140714 1;
%e A140714 3,1;
%e A140714 9,5,2;
%e A140714 28,19,12,5;
%e A140714 90,68,51,33,14;
%Y A140714 Cf. A000302, A000245, A000108, A140713.
%K A140714 nonn,tabl,more
%O A140714 2,2
%A A140714 _Emeric Deutsch_, May 29 2008