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 A128584 #9 May 29 2023 08:13:08 %S A128584 1,1,0,0,2,0,1,-2,3,0,0,0,0,4,0,1,0,0,-4,5,0,0,0,0,0,0,6,0,1,-2,3,-4, %T A128584 5,-6,7,0,0,2,-3,0,5,-6,0,8,0,1,-2,3,0,0,-6,7,-8,9,0,0,0,0,0,0,0,0,0, %U A128584 0,10,0,1,0,0,-4,5,-6,7,0,0,-10,11,0 %N A128584 A054521 * A128064 (unsigned). %C A128584 Row sums = phi(n), A000010: (1, 1, 2, 2, 4, 2, 6, 4, 6, 4, ...). %F A128584 A054521 * A128064 (unsigned) as infinite lower triangular matrices. %e A128584 First few rows of the triangle: %e A128584 1; %e A128584 1, 0; %e A128584 0, 2, 0; %e A128584 1, -2, 3, 0; %e A128584 0, 0, 0, 4, 0; %e A128584 1, 0, 0, -4, 5, 0; %e A128584 ... %Y A128584 Cf. A054521, A128064, A000010. %K A128584 tabl,sign %O A128584 1,5 %A A128584 _Gary W. Adamson_, Mar 11 2007 %E A128584 a(28) = 0 inserted and more terms from _Georg Fischer_, May 29 2023