A127574 Triangle T(n,k) = k*sigma(n) if k divides n, else 0.

1, 3, 6, 4, 0, 12, 7, 14, 0, 28, 6, 0, 0, 0, 30, 12, 24, 36, 0, 0, 72, 8, 0, 0, 0, 0, 0, 56, 15, 30, 0, 60, 0, 0, 0, 120, 13, 0, 39, 0, 0, 0, 0, 0, 117, 18, 36, 0, 0, 90, 0, 0, 0, 0, 180, 12, 0, 0, 0, 0, 0, 0, 0, 0, 0, 132, 28, 56, 84, 112, 0, 168, 0, 0, 0, 0, 0, 336

Offset

1,2

Links

Table of n, a(n) for n=1..78.

Formula

T(n,k) = Sum_{j=k..n} A130208(n,j)*A127093(j,k), product of the two infinite lower triangular matrices.

T(n,1) = A000203(n).

T(n,n) = A064987(n).

Example

First few rows of the triangle are:
   1;
   3,  6;
   4,  0, 12;
   7, 14,  0, 28;
   6,  0,  0,  0, 30;
  12, 24, 36,  0,  0, 72;
  ...

Crossrefs

Cf. A127093, A127573, A064987, A000203, A072861 (row sums).

Sequence in context: A265480 A309084 A288092 * A356501 A334279 A334278

Adjacent sequences: A127571 A127572 A127573 * A127575 A127576 A127577

Keyword

nonn,tabl

Author

Gary W. Adamson, Jan 19 2007

Status

approved