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 A117901 #3 Mar 30 2012 18:59:14 %S A117901 1,-1,1,0,-2,1,0,3,-2,1,0,0,0,-1,1,0,-6,3,0,-2,1,0,12,-6,0,3,-2,1,0,0, %T A117901 0,0,0,0,-1,1,0,-24,12,0,-6,3,0,-2,1,0,48,-24,0,12,-6,0,3,-2,1,0,0,0, %U A117901 0,0,0,0,0,0,-1,1,0,-96,48,0,-24,12,0,-6,3,0,-2,1,0,192,-96,0,48,-24,0,12,-6,0,3,-2,1 %N A117901 Inverse of number triangle A117898. %C A117901 Row sums are A117902. Diagonal sums are A117903. %F A117901 G.f.:(2x^6*y^2+x^5*y(2-y)+4x^4(1-y)-x^3(2y^2-3y+4)+x^2*y(y-2)+x(y-1)+1)/((1-4x^3)(1-x^3*y^3)) %e A117901 Triangle begins %e A117901 1, %e A117901 -1, 1, %e A117901 0, -2, 1, %e A117901 0, 3, -2, 1, %e A117901 0, 0, 0, -1, 1, %e A117901 0, -6, 3, 0, -2, 1, %e A117901 0, 12, -6, 0, 3, -2, 1, %e A117901 0, 0, 0, 0, 0, 0, -1, 1, %e A117901 0, -24, 12, 0, -6, 3, 0, -2, 1, %e A117901 0, 48, -24, 0, 12, -6, 0, 3, -2, 1 %K A117901 easy,sign,tabl %O A117901 0,5 %A A117901 _Paul Barry_, Apr 01 2006