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 A129240 #4 Feb 18 2022 22:31:30 %S A129240 1,2,2,4,0,3,6,5,0,4,9,0,3,0,5,12,9,4,4,0,6,16,0,3,0,5,0,7,20,14,4,9, %T A129240 0,6,0,8,25,0,8,0,5,0,7,0,9,30,20,4,9,6,6,0,8,0,10 %N A129240 A128174 * A129234. %C A129240 Left border = A002620 starting (1, 2, 4, 6, 9, 12, 16, ...). %F A129240 A128174 * A129234 as infinite lower triangular matrices. %e A129240 First few rows of the triangle: %e A129240 1; %e A129240 2, 2; %e A129240 4, 0, 3; %e A129240 6, 5, 0, 4; %e A129240 9, 0, 3, 0, 5; %e A129240 12, 9, 4, 4, 0, 6; %e A129240 16, 0, 3, 0, 5, 0, 7; %e A129240 ... %Y A129240 Cf. A128174, A129234, A002620. %K A129240 nonn,tabl %O A129240 1,2 %A A129240 _Gary W. Adamson_, Apr 05 2007