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 A101125 #14 Jan 20 2019 16:19:29
%S A101125 1,1,1,4,13,49,233,1240,7201,45521,311225,2285116,17909309,149080865,
%T A101125 1312597361,12180044528,118740086369,1212695223137,12942512039697,
%U A101125 144018843991220,1667526171728525,20053044685823697,250043383489271193
%N A101125 Row sums of a Chebyshev number triangle.
%C A101125 Row sums of A101124.
%H A101125 Seiichi Manyama, <a href="/A101125/b101125.txt">Table of n, a(n) for n = 0..533</a>
%H A101125 <a href="/index/Ch#Cheby">Index entries for sequences related to Chebyshev polynomials.</a>
%F A101125 a(n)=sum{k=0..n, if(k<n, T(n-k, k), if(k=n, 1, 0))} where T(n, k)=(n/2)sum{j=0..floor(n/2), C(n-j, j)(-1)^j*(2k)^(n-2j)}.
%t A101125 Table[Sum[ChebyshevT[k, n-k], {k, 0, n}], {n, 0, 30}] (* _Vaclav Kotesovec_, Jan 20 2019 *)
%o A101125 (PARI) {a(n) = sum(k=0, n, polchebyshev(k, 1, n-k))} \\ _Seiichi Manyama_, Jan 20 2019
%K A101125 easy,nonn
%O A101125 0,4
%A A101125 _Paul Barry_, Dec 02 2004