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 A143442 #5 Mar 19 2017 01:04:25 %S A143442 1,2,-2,3,-3,-3,4,-4,-4,0,5,-5,-5,0,-5,6,-6,-6,0,-6,6,7,-7,-7,0,-7,7, %T A143442 -7,8,-8,-8,0,-8,8,-8,0,9,-9,-9,0,-9,9,-9,0,0,10,-10,-10,0,-10,10,-10, %U A143442 0,0,10,11,-11,-11,0,-11,11,-11,0,0,11,-11 %N A143442 Triangle read by rows, A127648 * A000012 * A128407, 1 <= k <= n. %C A143442 Row sums = A143443, n * (A002321, the Mertens function) = (1, 0, -3, -4, -10, -6, ...). %C A143442 Right border = n*mu(n). %F A143442 Triangle read by rows, A127648 * A000012 * A128407, 1 <= k <= n; where A127648 = an infinite lower triangular matrix with (1, 2, 3, ...) in the main diagonal, the rest zeros. A128407 = diagonalized mu(n) matrix. %e A143442 First few rows of the triangle = %e A143442 1; %e A143442 2, -2; %e A143442 3, -3, -3; %e A143442 4, -4, -4, 0; %e A143442 5, -5, -5, 0, -5; %e A143442 6, -6, -6, 0, -6, 6; %e A143442 7, -7, -7, 0, -7, 7, -7; %e A143442 ... %Y A143442 Cf. A002321, A008683, A127648, A128407, A143443. %K A143442 tabl,sign %O A143442 1,2 %A A143442 _Gary W. Adamson_, Aug 15 2008