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 A131331 #3 Mar 30 2012 17:25:21 %S A131331 1,0,1,1,0,1,-1,2,0,1,2,-1,3,0,1,-3,4,-1,4,0,1,5,-4,7,-1,5,0,1,-8,9, %T A131331 -5,11,-1,6,0,1,13,-12,16,-6,16,-1,7,0,1,-21,22,-17,27,-7,22,-1,8,0,1 %N A131331 A046854 * A000012(signed). %C A131331 Row sums = A094967: (1, 1, 2, 2, 5, 5, 13, 13, 34, 34...). %F A131331 A046854 * A000012(signed by columns, + - + -...). %e A131331 First few rows of the triangle are: %e A131331 1; %e A131331 0, 1; %e A131331 1, 0, 1; %e A131331 -1, 2, 0, 1; %e A131331 2, -1, 3, 0, 1; %e A131331 -3, 4, -1, 4, 0, 1; %e A131331 5, -4, 7, -1, 5, 0, 1; %e A131331 -8, 9, -5, 11, -1, 6, 0, 1; %e A131331 ... %Y A131331 Cf. A046854, A000012, A094967. %K A131331 tabl,sign %O A131331 0,8 %A A131331 _Gary W. Adamson_, Jun 29 2007