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 A131307 #8 Feb 26 2022 10:50:32 %S A131307 1,2,3,3,2,5,4,5,2,7,5,4,7,2,9,6,7,4,9,2,11,7,6,9,4,11,2,13,8,9,6,11, %T A131307 4,13,2,15,9,8,11,6,13,4,15,2,17,10,11,8,13,6,15,4,17,2,19 %N A131307 (A127701 * A000012 + A000012(signed) * A127701) - A000012. %C A131307 Row sums = A035608: (1, 5, 10, 18, 27, 39, 52, ...). %F A131307 (A127701 * A000012 + A000012(signed) * A127701) - A000012; as infinite lower triangular matrices, where A000012(signed) = (1; -1,1; 1,-1,1; -1,1,-1,1; ...). %e A131307 First few rows of the triangle: %e A131307 1; %e A131307 2, 3; %e A131307 3, 2, 5; %e A131307 4, 5, 2, 7; %e A131307 5, 4, 7, 2, 9; %e A131307 6, 7, 4, 9, 2, 11; %e A131307 7, 6, 9, 4, 11, 2, 13; %e A131307 8, 9, 6, 11, 4, 13, 2, 15; %e A131307 9, 8, 11, 6, 13, 4, 15, 2, 17; %e A131307 10, 11, 8, 13, 6, 15, 4, 17, 2, 19; %e A131307 ... %Y A131307 Cf. A000012, A127701, A035608. %K A131307 nonn,tabl,more %O A131307 1,2 %A A131307 _Gary W. Adamson_, Sep 30 2007