A127571 Triangle T(n,k) = phi(n/k)*sigma(k) if k divides n, else 0.

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, 0, 15, 6, 0, 8, 0, 0, 0, 0, 0, 13, 4, 12, 0, 0, 6, 0, 0, 0, 0, 18

Offset: 1

Author

Gary W. Adamson, Jan 19 2007

Keywords

• nonn
• tabl

Examples

			First few rows of the triangle are:
1;
1, 3;
2, 0, 4;
2, 3, 0, 7;
4, 0, 0, 0, 6;
2, 6, 4, 0, 0, 12;
...
		

Crossrefs

Cf. A000203, A000010, A038040 (row sums), A054523.

Formula

T(n,k) = sum_{j=k..n} A054523(n,j)* A130208(j,k), product of the two infinite lower triangular matrices.

T(n,1) = A000010(n).

T(n,n) = A000203(n).