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 A106190 #5 Jul 30 2015 22:48:09
%S A106190 1,-2,1,-2,-2,1,-4,-2,-2,1,-10,-4,-2,-2,1,-28,-10,-4,-2,-2,1,-84,-28,
%T A106190 -10,-4,-2,-2,1,-264,-84,-28,-10,-4,-2,-2,1,-858,-264,-84,-28,-10,-4,
%U A106190 -2,-2,1,-2860,-858,-264,-84,-28,-10,-4,-2,-2,1,-9724,-2860,-858,-264,-84,-28,-10,-4,-2,-2,1,-33592,-9724,-2860,-858
%N A106190 Triangle read by rows: T(n,k) = binomial(2(n-k),n-k)/(1-2(n-k)).
%C A106190 Sequence array for expansion of sqrt(1-4x).
%C A106190 Row sums are A106191. Diagonal sums are A106192. Sequence array for A002420. Inverse of number triangle A106187.
%C A106190 Riordan array (sqrt(1-4x),x).
%e A106190 Triangle begins
%e A106190 1;
%e A106190 -2,1;
%e A106190 -2,-2,1;
%e A106190 -4,-2,-2,1;
%e A106190 -10,-4,-2,-2,1;
%e A106190 -28,-10,-4,-2,-2,1;
%t A106190 T[n_, k_] := Binomial[2(n - k), n - k]/(1 - 2(n - k)); Flatten[ Table[ T[n, k], {n, 0, 10}, {k, 0, n}]] (* _Robert G. Wilson v_, Apr 25 2005 *)
%K A106190 easy,sign,tabl
%O A106190 0,2
%A A106190 _Paul Barry_, Apr 24 2005
%E A106190 More terms from _Robert G. Wilson v_, Apr 25 2005