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 A117185 #3 Mar 30 2012 18:59:14 %S A117185 1,-1,1,-2,-1,1,3,-3,-1,1,1,4,-4,-1,1,-4,4,5,-5,-1,1,1,-8,8,6,-6,-1,1, %T A117185 3,-3,-13,13,7,-7,-1,1,-2,11,-11,-19,19,8,-8,-1,1,-1,1,24,-24,-26,26, %U A117185 9,-9,-1,1,1,-12,12,43,-43,-34,34,10,-10,-1,1 %N A117185 Riordan array ((1-x^2)/(1+x+2x^2+x^3+x^4),x/(1+x^2)). %C A117185 Row sums are A117188. Diagonal sums are A099837. Inverse of A117184. %e A117185 Triangle begins %e A117185 1, %e A117185 -1, 1, %e A117185 -2, -1, 1, %e A117185 3, -3, -1, 1, %e A117185 1, 4, -4, -1, 1, %e A117185 -4, 4, 5, -5, -1, 1, %e A117185 1, -8, 8, 6, -6, -1, 1, %e A117185 3, -3, -13, 13, 7, -7, -1, 1 %K A117185 easy,sign,tabl %O A117185 0,4 %A A117185 _Paul Barry_, Mar 01 2006