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 A098508 #15 Aug 30 2024 16:32:15
%S A098508 0,0,1,3,3,5,5,7,14,18,45,55,33,39,91,7,4,68,51,57,19,7,77,253,23,25,
%T A098508 325,351,27,29,435,465,248,88,187,85,45,333,703,741,39,41,41,43,473,
%U A098508 11,23,1081,94,98,1225,425,221,689,477,495,385,133,551,1711,295,305,1891
%N A098508 Second column of the inverse of a Catalan scaled binomial matrix (A098505).
%H A098508 Paolo Xausa, <a href="/A098508/b098508.txt">Table of n, a(n) for n = 0..10000</a>
%F A098508 a(n) = numerator((n+1)*binomial(n, 2)/binomial(2*n, n));
%F A098508 a(n) = numerator((n-1)*n*(n+1)/(2*binomial(2*n, n))).
%t A098508 Table[Numerator[n*(n^2 - 1)/(2*Binomial[2*n, n])], {n, 0, 100}] (* _Paolo Xausa_, Aug 30 2024 *)
%Y A098508 Second column of A098505.
%K A098508 easy,nonn
%O A098508 0,4
%A A098508 _Paul Barry_, Sep 11 2004