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 A144379 #2 Mar 30 2012 17:25:32 %S A144379 1,1,1,1,1,2,1,1,1,2,1,1,2,2,4,1,1,1,1,1,2,1,1,2,2,4,2,6,1,1,1,2,2,2, %T A144379 3,4,1,1,2,1,3,2,4,3,6,1,1,1,2,2,1,2,3,2,4,1,1,2,2,4,2,6,4,6,4,10,1,1, %U A144379 1,1,1,2,2,3,3,2,3,4,1,1,2,2,4,2,6,4,6,4,10,4,12,1,1,1,2,2,2,3,3,2,3,4,3,5 %N A144379 Triangle read by rows, first n terms of an array formed by A054521 * A054521(transform). %C A144379 Right border = phi(n): (1, 1, 2, 2, 4, 2, 6, 4, 6, 4, 10,...). %C A144379 Row sums = A125728: (1, 2, 4, 5, 10, 7, 18, 16, 23,...) = the number of positive integers less <=k coprime to both k and n. %F A144379 Given A054521 as an infinite lower triangular matrix, perform A054521(transform). Multiply the result by A054521 getting an array, then extract the first n terms of each row to form a new triangle. %e A144379 A054521 * A054521(transform) = %e A144379 1, 1, 1, 1, 1, 1, 1,... %e A144379 1, 1, 1, 1, 1, 1, 1,... %e A144379 1, 1, 2, 1, 2, 1, 2,... %e A144379 1, 1, 1, 2, 2, 1, 2,... %e A144379 1, 1, 2, 2, 4, 1, 4,... %e A144379 ... %e A144379 Then extract the lower half of the array including the diagonal, A000010, phi(n); getting triangle A144379: %e A144379 1; %e A144379 1, 1; %e A144379 1, 1, 2 %e A144379 1, 1, 1, 2; %e A144379 1, 1, 2, 2, 4; %e A144379 1, 1, 1, 1, 1, 2; %e A144379 1, 1, 2, 2, 4, 2, 6; %e A144379 1, 1, 1, 2, 2, 2, 3, 4; %e A144379 1, 1, 2, 1, 3, 2, 4, 3, 6; %e A144379 1, 1, 1, 2, 2, 1, 2, 3, 2, 4; %e A144379 1, 1, 2, 2, 4, 2, 6, 4, 6, 4, 10; %e A144379 ... %Y A144379 A054521, Cf. A000010, A125728 %K A144379 nonn,tabl %O A144379 1,6 %A A144379 _Gary W. Adamson_, Sep 19 2008