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 A117362 #3 Mar 30 2012 18:59:14 %S A117362 1,-2,1,0,-3,1,0,2,-4,1,0,0,5,-5,1,0,0,-2,9,-6,1,0,0,0,-7,14,-7,1,0,0, %T A117362 0,2,-16,20,-8,1,0,0,0,0,9,-30,27,-9,1,0,0,0,0,-2,25,-50,35,-10,1,0,0, %U A117362 0,0,0,-11,55,-77,44,-11,1 %N A117362 Riordan array (1-2x,x(1-x)). %C A117362 A signed version of A113214. Inverse of A092392. Row sums are A100051(n+1) with g.f. (1-2x)/(1-x+x^2). Diagonal sums are A117363. %F A117362 Number triangle T(n,k)=(-1)^(n-k)(C(k,n-k)+2*C(k, n-k-1)) %e A117362 Triangle begins %e A117362 1, %e A117362 -2, 1, %e A117362 0, -3, 1, %e A117362 0, 2, -4, 1, %e A117362 0, 0, 5, -5, 1, %e A117362 0, 0, -2, 9, -6, 1, %e A117362 0, 0, 0, -7, 14, -7, 1, %e A117362 0, 0, 0, 2, -16, 20, -8, 1 %K A117362 easy,sign,tabl %O A117362 0,2 %A A117362 _Paul Barry_, Mar 10 2006