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 A128140 #5 Feb 15 2022 01:58:32 %S A128140 1,3,2,7,5,3,13,10,7,4,21,17,13,9,5,31,26,21,16,11,6,43,37,31,25,19, %T A128140 13,7,57,50,43,36,29,22,15,8,73,65,57,49,41,33,25,17,9,91,82,73,64,55, %U A128140 46,37,28,19,10 %N A128140 A128132 * A004736. %C A128140 Row sums = A006003, starting (1, 5, 15, 34, 65, 111, ...). Left border = A002061: (1, 3, 7, 13, 21, 31, 43, ...) A128139 = A004736 * A128132 %F A128140 A128132 * A004736 as infinite lower triangular matrices. %e A128140 First few rows of the triangle: %e A128140 1; %e A128140 3, 2; %e A128140 7, 5, 3; %e A128140 13, 10, 7, 4; %e A128140 21, 17, 13, 9, 5; %e A128140 31, 26, 21, 16, 11, 6; %e A128140 43, 37, 31, 25, 19, 13, 7; %e A128140 ... %Y A128140 Cf. A128132, A004736, A006003, A004006, A128139. %K A128140 nonn,tabl %O A128140 1,2 %A A128140 _Gary W. Adamson_, Feb 16 2007