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 A135151 #6 Mar 27 2022 18:27:33 %S A135151 1,1,2,2,2,3,1,3,3,4,2,2,4,4,5,1,3,3,5,5,6,2,2,4,4,6,6,7,1,3,3,5,5,7, %T A135151 7,8,2,2,4,4,6,6,8,8,9,1,3,3,5,5,7,7,9,9,10 %N A135151 A002260 + A128174 - I, I = Identity matrix. %C A135151 A135152 is a companion triangle, both having row sums = A047838: (1, 3, 7, 11, 17, 23, 31, 39, ...). %F A135151 A002260 + A128174 - I, where I = Identity matrix, A002260 = (1; 1,2; 1,2,3; ...) and A128174 = (1; 0,1; 1,0,1; 0,1,0,1; ...). %e A135151 First few rows of the triangle: %e A135151 1; %e A135151 1, 2; %e A135151 2, 2, 3; %e A135151 1, 3, 3, 4; %e A135151 2, 2, 4, 4, 5; %e A135151 1, 3, 3, 5, 5, 6; %e A135151 2, 2, 4, 4, 6, 6, 7; %e A135151 ... %Y A135151 Cf. A002260, A047838, A135152. %K A135151 nonn,tabl %O A135151 1,3 %A A135151 _Gary W. Adamson_, Nov 21 2007