A127570 Triangle T(n,k) = sigma(k) if k|n, otherwise T(n,k)=0; 1 <= k <= n.

1, 1, 3, 1, 0, 4, 1, 3, 0, 7, 1, 0, 0, 0, 6, 1, 3, 4, 0, 0, 12, 1, 0, 0, 0, 0, 0, 8, 1, 3, 0, 7, 0, 0, 0, 15, 1, 0, 4, 0, 0, 0, 0, 0, 13, 1, 3, 0, 0, 6, 0, 0, 0, 0, 18, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 12, 1, 3, 4, 7, 0, 12, 0, 0, 0, 0, 0, 28, 1

Offset

1,3

Links

Table of n, a(n) for n=1..79.

Formula

T(n,k) = Sum_{j=k..n} A051731(n,j)*A130208(j,k) = A051731(n,k)*A000203(k).

Example

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

Crossrefs

Cf. A000203 (sigma, diagonal n=k), A007429 (row sums), A051731.

Sequence in context: A346369 A127569 A117372 * A340583 A292506 A212186

Adjacent sequences: A127567 A127568 A127569 * A127571 A127572 A127573

Keyword

nonn,tabl,easy

Author

Gary W. Adamson, Jan 19 2007

Status

approved