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 A137639 #7 Apr 02 2022 09:25:39 %S A137639 1,2,1,3,0,1,5,2,0,1,7,1,0,0,1,11,3,2,0,0,1,15,2,1,0,0,0,1,22,6,1,2,0, %T A137639 0,0,1,30,5,3,1,0,0,0,0,1,42,9,2,1,2,0,0,0,0,1,56,9,3,1,1,0,0,0,0,0,1, %U A137639 77,16,6,3,1,2,0,0,0,0,0,1 %N A137639 Triangle read by rows, A026794 * A051731. %C A137639 Left border = A000041 starting with offset 1: (1, 2, 3, 5, 7, 11, 15, ...). %C A137639 Row sums = A137640: (1, 3, 4, 8, 9, 17, 19, ...). %F A137639 A026794 * A051731 as infinite lower triangular matrices. %e A137639 First few rows of the triangle: %e A137639 1; %e A137639 2, 1; %e A137639 3, 0, 1; %e A137639 5, 2, 0, 1; %e A137639 7, 1, 0, 0, 1; %e A137639 11, 3, 2, 0, 0, 1; %e A137639 15, 2, 1, 0, 0, 0, 1; %e A137639 22, 6, 1, 2, 0, 0, 0, 1; %e A137639 30, 5, 3, 1, 0, 0, 0, 0, 1; %e A137639 ... %Y A137639 Cf. A000041, A137640, A026794, A051731. %K A137639 nonn,tabl %O A137639 1,2 %A A137639 _Gary W. Adamson_, Jan 31 2008