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 A128521 #5 Feb 18 2022 22:19:31 %S A128521 1,0,1,1,1,1,0,1,1,1,1,2,2,1,1,0,0,1,2,1,1,1,3,3,2,2,1,1,0,0,1,2,2,2, %T A128521 1,1,1,3,3,3,3,2,2,1,1,0,-1,1,2,2,3,2,2,1,1 %N A128521 A128174 * A054525 * A000012. %C A128521 Row sums = A106477: (1, 1, 3, 3, 7, 5, 13, 9, 19, 13, ...). A128522 = A054525 * A128174 * A000012. %F A128521 A128174 * A054525 * A000012 as infinite lower triangular matrices. %e A128521 First few rows of the triangle: %e A128521 1; %e A128521 0, 1; %e A128521 1, 1, 1; %e A128521 0, 1, 1, 1; %e A128521 1, 2, 2, 1, 1; %e A128521 0, 0, 1, 2, 1, 1; %e A128521 1, 3, 3, 2, 2, 1, 1; %e A128521 0, 0, 1, 2, 2, 2, 1, 1; %e A128521 ... %Y A128521 Cf. A128174, A054525, A000012, A106477, A128522. %K A128521 tabl,sign %O A128521 1,12 %A A128521 _Gary W. Adamson_, Mar 07 2007