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 A093421 #19 Oct 22 2019 04:20:58
%S A093421 1,1,3,1,1,1,1,1,1,5,1,3,1,1,1,1,1,1,1,1,7,1,1,1,1,1,1,1,1,3,1,1,1,1,
%T A093421 1,1,1,1,1,5,1,1,1,1,1,1,1,1,1,1,1,1,1,1,11,1,3,1,1,1,1,1,1,1,1,1,1,1,
%U A093421 1,1,1,1,1,1,1,1,1,13,1,1,1,1,1,7,1,1,1,1,1,1,1,1,3,1,5,1,1,1,1,1,1,1,1,1,1
%N A093421 Triangle read by rows: T(n,k) is the denominator of f(n, k) = (Product_{i = 0..k-1} (n-i))/(Sum_{i = 1..k} i) for 1 <= k <= n.
%F A093421 T(n,n) = denominator(f(n, n)) = denominator(2*(n-1)!/(n+1)).
%e A093421 Triangle T(n,k) (with rows n >= 1 and columns k >= 1) begins as follows:
%e A093421 1;
%e A093421 1, 3;
%e A093421 1, 1, 1;
%e A093421 1, 1, 1, 5;
%e A093421 1, 3, 1, 1, 1;
%e A093421 1, 1, 1, 1, 1, 7;
%e A093421 1, 1, 1, 1, 1, 1, 1;
%e A093421 1, 3, 1, 1, 1, 1, 1, 1;
%e A093421 1, 1, 1, 5, 1, 1, 1, 1, 1;
%e A093421 1, 1, 1, 1, 1, 1, 1, 1, 1, 11;
%e A093421 ...
%Y A093421 Cf. A090585, A090586, A093415, A093420 (numerators), A093423.
%K A093421 nonn,easy,frac,tabl,less
%O A093421 1,3
%A A093421 _Amarnath Murthy_, Mar 30 2004
%E A093421 Edited and extended by _David Wasserman_, Aug 29 2006