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 A128715 #3 Mar 30 2012 17:25:20 %S A128715 1,2,2,3,1,3,4,2,2,4,5,3,5,3,5,6,4,9,9,4,6,7,5,14,19,14,5,7,8,6,20,34, %T A128715 34,20,6,8,9,7,27,55,69,55,27,7,9,10,8,35,83,125,125,83,35,8,10 %N A128715 A131830 + A103451 - A000012 as infinite lower triangular matrices. %C A128715 Row sums are (apart from the first row) given by A005126. %e A128715 First few rows of the triangle are: %e A128715 1; %e A128715 2, 2; %e A128715 3, 1, 3; %e A128715 4, 2, 2, 4; %e A128715 5, 3, 5, 3, 5; %e A128715 6, 4, 9, 9, 4, 6; %e A128715 7, 5, 14, 19, 14, 5, 7; %e A128715 8, 6, 20, 34, 34, 20, 6, 8; %e A128715 9, 7, 27, 55, 69, 55, 27, 7, 9; %e A128715 ... %Y A128715 Cf. A131830, A103451, A000012, A005126. %K A128715 nonn,tabl %O A128715 0,2 %A A128715 _Gary W. Adamson_, Aug 09 2007