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 A128431 #5 Feb 18 2022 22:18:14 %S A128431 1,1,0,1,-1,0,1,0,-1,0,1,-1,-1,0,0,1,0,0,0,-1,0,1,-1,-1,0,-1,1,0,1,0, %T A128431 -1,0,-1,0,-1,0,1,-1,0,0,-1,0,-1,0,0,1,0,-1,0,0,0,-1,0,0,0 %N A128431 Triangle read by rows: A054521 * A128407. %C A128431 Row sums = A112399: (1, 1, 0, 0, -1, 0, -1, -2, -2, -1, ...). %F A128431 A054521 * A128407 as infinite lower triangular matrices. %e A128431 First few rows of the triangle: %e A128431 1; %e A128431 1, 0; %e A128431 1, -1, 0; %e A128431 1, 0, -1, 0; %e A128431 1, -1, -1, 0, 0; %e A128431 1, 0, 0, 0, -1, 0; %e A128431 1, -1, -1, 0, -1, 1, 0; %Y A128431 Cf. A054521, A128407, A112399, A008683. %K A128431 tabl,sign %O A128431 1,1 %A A128431 _Gary W. Adamson_, Mar 03 2007