A127572 - OEIS

A127572

Triangle, T(n,k) = sigma(k) * n/k if k|n, T(n,k) = 0 otherwise.

1, 2, 3, 3, 0, 4, 4, 6, 0, 7, 5, 0, 0, 0, 6, 6, 9, 8, 0, 0, 12, 7, 0, 0, 0, 0, 0, 8, 8, 12, 0, 14, 0, 0, 0, 15, 9, 0, 12, 0, 0, 0, 0, 0, 13, 10, 15, 0, 0, 12, 0, 0, 0, 0, 18

(list; table; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

Table of n, a(n) for n=1..55.

FORMULA

A126988 * M, where M = an infinite matrix with sigma(n) in the main diagonal and the rest zeros.

EXAMPLE

First few rows of the triangle are:

2, 3;

3, 0, 4;

4, 6, 0, 7;

5, 0, 0, 0, 6;

6, 9, 8, 0, 0, 12;

...

CROSSREFS

Main diagonal = sigma(n), A000203; row sums = A060640.

Cf. A126988.

Sequence in context: A192498 A360665 A308178 * A021815 A238525 A359788

Adjacent sequences: A127569 A127570 A127571 * A127573 A127574 A127575

KEYWORD

nonn,tabl

AUTHOR

Gary W. Adamson, Jan 19 2007

EXTENSIONS

Edited by Franklin T. Adams-Watters, Aug 24 2011

STATUS

approved