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 A256551 #7 Apr 19 2015 08:50:29 %S A256551 1,0,1,0,-1,1,0,1,-3,1,0,1,6,-6,1,0,-15,10,20,-10,1,0,48,-225,50,50, %T A256551 -15,1,0,581,1008,-1575,175,105,-21,1,0,-11069,16268,9408,-7350,490, %U A256551 196,-28,1,0,20784,-398484,195216,56448,-26460,1176,336,-36,1 %N A256551 Triangle read by rows, T(n,k) matrix inverse of A256550, for n>=0 and 0<=k<=n. %F A256551 T(n+1,n) = -A000217(n). %F A256551 T(n+2,n) = A002415(n+1). %F A256551 For T(n,1) compare A006542. %e A256551 Triangle starts: %e A256551 [1] %e A256551 [0, 1] %e A256551 [0, -1, 1] %e A256551 [0, 1, -3, 1] %e A256551 [0, 1, 6, -6, 1] %e A256551 [0, -15, 10, 20, -10, 1] %e A256551 [0, 48, -225, 50, 50, -15, 1] %e A256551 [0, 581, 1008, -1575, 175, 105, -21, 1] %Y A256551 Cf. A000217, A002415, A006542, A256550. %K A256551 sign,tabl,easy %O A256551 0,9 %A A256551 _Peter Luschny_, Apr 01 2015