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 A117200 #2 Mar 30 2012 18:59:14 %S A117200 1,-1,1,-1,0,1,1,-1,0,1,0,0,0,0,1,2,-1,-1,0,0,1,0,0,0,0,0,0,1,-1,1,0, %T A117200 -1,0,0,0,1,1,0,-1,0,0,0,0,0,1,0,0,0,0,-1,0,0,0,0,1,0,0,0,0,0,0,0,0,0, %U A117200 0,1,-3,2,1,-1,0,-1,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,-1,0,0,0,0,0,0,1,0,0,0,0,-1,0,0,0,0,0,0,0,0,0,1,1 %N A117200 Inverse of number triangle (1,x)+(x,x^2)+(x^2,x^3). %C A117200 Inverse of A117198. Row sums are A117201. %e A117200 Triangle begins %e A117200 1, %e A117200 -1, 1, %e A117200 -1, 0, 1, %e A117200 1, -1, 0, 1, %e A117200 0, 0, 0, 0, 1, %e A117200 2, -1, -1, 0, 0, 1, %e A117200 0, 0, 0, 0, 0, 0, 1, %e A117200 -1, 1, 0, -1, 0, 0, 0, 1, %e A117200 1, 0, -1, 0, 0, 0, 0, 0, 1 %K A117200 sign,tabl %O A117200 0,16 %A A117200 _Paul Barry_, Mar 02 2006