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 A168261 #7 Jan 22 2023 08:37:31 %S A168261 1,1,1,0,0,2,1,1,0,2,0,0,0,0,4,0,0,2,0,0,4,0,0,0,0,0,0,6,1,1,0,2,0,0, %T A168261 0,6,0,0,0,0,0,0,0,0,10,0,0,0,0,4,0,0,0,0,10,0,0,0,0,0,0,0,0,0,0,14,0, %U A168261 0,2,0,0,4,0,0,0,0,0,14,0,0,0,0,0,0,0,0,0,0,0,0,20 %N A168261 Triangle read by rows, A115361 * the diagonalized variant of A018819. %C A168261 Row sums = A018819 starting with offset 1; (1, 2, 2, 4, 4, 6, 6, 10, 10,...). %C A168261 Equals the eigensequence of triangle A115361. %C A168261 Rightmost diagonal = A018819. %C A168261 Sum of n-th row terms = rightmost term of next row. %F A168261 Equals M*Q as infinite lower triangular matrices, where M = triangle A115361, and Q = the diagonalized variant of A018819 such that (1, 1, 2, 2, 4, 4, 6, 6,...) = rightmost diagonal with the rest zeros. %e A168261 First few rows of the triangle = %e A168261 1; %e A168261 1, 1; %e A168261 0, 0, 2; %e A168261 1, 1, 0, 2; %e A168261 0, 0, 0, 0, 4; %e A168261 0, 0, 2, 0, 0, 4; %e A168261 0, 0, 0, 0, 0 0, 6; %e A168261 1, 1, 0, 2, 0, 0, 0, 6; %e A168261 0, 0, 0, 0, 0, 0, 0, 0, 10; %e A168261 0, 0, 0, 0, 4, 0, 0, 0, 0, 10; %e A168261 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 14; %e A168261 0, 0, 2, 0, 0, 4, 0, 0, 0, 0, 0, 14; %e A168261 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 20; %e A168261 0, 0, 0, 0, 0, 0, 6, 0, 0, 0, 0, 0, 0, 20; %e A168261 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 26; %e A168261 1, 1, 0, 2, 0, 0, 0, 6, 0, 0, 0, 0, 0, 0, 0, 26; %e A168261 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 36; %e A168261 ... %Y A168261 Cf. A115361, A018819. %K A168261 nonn,tabl %O A168261 1,6 %A A168261 _Gary W. Adamson_, Nov 21 2009