login
Triangle T(n,k) = phi(n) if k|n, =0 otherwise.
0

%I #6 Mar 30 2012 17:25:15

%S 1,1,1,2,0,2,2,2,0,2,4,0,0,0,4,2,2,2,0,0,2,6,0,0,0,0,0,6,4,4,0,4,0,0,

%T 0,4,6,0,6,0,0,0,0,0,6,4,4,0,0,4,0,0,0,0,4

%N Triangle T(n,k) = phi(n) if k|n, =0 otherwise.

%F T(n,k) = A000010(n)*A051731(n,k), 1<=k<=n.

%e First few rows of the triangle are:

%e 1;

%e 1, 1;

%e 2, 0, 2;

%e 2, 2, 0, 2;

%e 4, 0, 0, 0, 4;

%e 2, 2, 2, 0, 0, 2;

%e 6, 0, 0, 0, 0, 0, 6;

%e 4, 4, 0, 4, 0, 0, 0, 4;

%e ...

%Y Cf. A051731, A062355 (row sums), A000010 (phi).

%K nonn,tabl,easy

%O 1,4

%A _Gary W. Adamson_, Jan 17 2007