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 A127506 #4 Mar 30 2012 17:39:19 %S A127506 1,1,0,1,1,0,1,0,2,0,1,1,2,2,0,1,0,0,0,4,0,1,1,2,2,4,2,0,1,0,2,0,4,0, %T A127506 6,0,1,1,0,2,4,0,6,4,0,1,0,2,0,0,0,6,0,6,0 %N A127506 Triangle read by rows: T(n,k) = A054521(n,k)*A000010(k), 1<=k<=n . %C A127506 Row sums = A053570. %F A127506 A054521 * M, as infinite lower triangular matrices; M = phi(n) in the main diagonal and the rest zeros. %e A127506 First few rows of the triangle are: %e A127506 1; %e A127506 1, 0; %e A127506 1, 1, 0; %e A127506 1, 0, 2, 0; %e A127506 1, 1, 2, 2, 0; %e A127506 1, 0, 0, 0, 4, 0; %e A127506 1, 1, 2, 2, 4, 2, 0; %e A127506 ... %Y A127506 Cf. A054521, A000010, A053570. %K A127506 nonn,tabl %O A127506 1,9 %A A127506 _Gary W. Adamson_, Jan 17 2007 %E A127506 Edited by _R. J. Mathar_, Jan 09 2008