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 A131256 #4 Feb 18 2022 22:34:58 %S A131256 1,0,1,1,1,1,0,2,1,1,1,2,3,1,1,0,3,4,3,1,1,1,3,7,5,3,1,1,0,4,9,10,5,3, %T A131256 1,11,4,13,16,11,5,3,1,1,0,5,16,26,20,11,5,3,1,1 %N A131256 A000012(signed) * A052509. %C A131256 Row sums = A052952: (1, 1, 3, 4, 8, 12, 21, 33, ...). A131257 = A052509 * A000012(signed). %F A131256 A000012(signed) * A052509, where the signed version of A000012 = (1; -1,1; 1,-1,1; ...). %e A131256 First few rows of the triangle: %e A131256 1; %e A131256 0, 1; %e A131256 1, 1, 1; %e A131256 0, 2, 1, 1; %e A131256 1, 2, 3, 1, 1; %e A131256 0, 3, 4, 3, 1, 1; %e A131256 1, 3, 7, 5, 3, 1, 1; %e A131256 ... %Y A131256 Cf. A052509, A000012, A131257. %K A131256 nonn,tabl %O A131256 0,8 %A A131256 _Gary W. Adamson_, Jun 23 2007