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 A131768 #6 Mar 04 2022 01:25:25 %S A131768 1,3,1,5,5,1,7,11,7,1,9,19,19,9,1,11,29,39,29,11,1,13,41,69,69,41,13, %T A131768 1,15,55,111,139,111,55,15,1,17,71,167,251,251,167,71,17,1,19,89,239, %U A131768 419,503,419,239,89,19,1 %N A131768 2*(A007318 * A097807) - A000012. %C A131768 Row sums = A000295, the Eulerian numbers, starting (1, 4, 11, 26, 57, 120, ...). %F A131768 2*(A007318 * A097807) - A000012 as infinite lower triangular matrices. %e A131768 First few rows of the triangle: %e A131768 1; %e A131768 3, 1; %e A131768 5, 5, 1; %e A131768 7, 11, 7, 1; %e A131768 9, 19, 19, 9, 1; %e A131768 11, 29, 39, 29, 11, 1; %e A131768 13, 41, 69, 69, 41, 13, 1; %e A131768 15, 55, 111, 139, 111, 55, 15, 1; %e A131768 ... %Y A131768 Cf. A007318, A097807, A000012, A000295. %K A131768 nonn,tabl %O A131768 0,2 %A A131768 _Gary W. Adamson_, Jul 13 2007