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 A127571 #6 Sep 17 2013 15:07:08
%S A127571 1,1,3,2,0,4,2,3,0,7,4,0,0,0,6,2,6,4,0,0,12,6,0,0,0,0,0,8,4,6,0,7,0,0,
%T A127571 0,15,6,0,8,0,0,0,0,0,13,4,12,0,0,6,0,0,0,0,18
%N A127571 Triangle T(n,k) = phi(n/k)*sigma(k) if k divides n, else 0.
%F A127571 T(n,k) = sum_{j=k..n} A054523(n,j)* A130208(j,k), product of the two infinite lower triangular matrices.
%F A127571 T(n,1) = A000010(n).
%F A127571 T(n,n) = A000203(n).
%e A127571 First few rows of the triangle are:
%e A127571 1;
%e A127571 1, 3;
%e A127571 2, 0, 4;
%e A127571 2, 3, 0, 7;
%e A127571 4, 0, 0, 0, 6;
%e A127571 2, 6, 4, 0, 0, 12;
%e A127571 ...
%Y A127571 Cf. A000203, A000010, A038040 (row sums), A054523.
%K A127571 nonn,tabl
%O A127571 1,3
%A A127571 _Gary W. Adamson_, Jan 19 2007