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 A055136 #9 Apr 14 2017 03:01:15
%S A055136 1,0,1,-1,-1,1,-2,0,-2,1,-3,0,3,-3,1,-4,0,-4,8,-4,1,-5,0,5,-20,15,-5,
%T A055136 1,-6,0,-6,48,-54,24,-6,1,-7,0,7,-112,189,-112,35,-7,1,-8,0,-8,256,
%U A055136 -648,512,-200,48,-8,1,-9,0,9,-576,2187,-2304,1125,-324,63,-9,1,-10,0
%N A055136 Triangle: a(n,k) = A055135(n,k)/C(n,k).
%F A055136 n, k>1: a(n, k) = (-1)^(n+k)*(n-1)*(k-1)^(n-k-1).
%e A055136 1;
%e A055136 0,1;
%e A055136 -1,-1,1;
%e A055136 -2,0,-2,1;
%e A055136 -3,0,3,-3,1; ...
%t A055136 a[n_, k_] := (-1)^(n+k)*(n-1)*(k-1)^(n-k-1); a[1, 1] = a[2, 1] = 1; Table[ a[n, k], {n, 0, 12}, {k, 0, n}] // Flatten (* _Jean-François Alcover_, Apr 14 2017 *)
%K A055136 sign,tabl
%O A055136 0,7
%A A055136 _Christian G. Bower_, Apr 25 2000