1,2

Row sums = sigma(n), A000203: (1, 3, 4, 7, 6, 12, 8,...). Left border = A158901: (1, 2, 3, 5, 5, 9, 7,...).

Triangle read by rows, A051731 * A158221; where A051731 = the inverse Mobius transform and A158221 = an infinite lower triangular matrix with (1, 1, 2, 3, 4, 5,...) as the left border and (1, 1, 1,...) as the right border.

First few rows of the triangle =

1;

2, 1;

3, 0, 1;

5, 1, 0, 1;

5, 0, 0, 0, 1;

9, 1, 1, 0, 0, 1;

7, 0, 0, 0, 0, 0, 1;

12, 1, 0, 1, 0, 0, 0, 1

11, 0, 1, 0, 0, 0, 0, 0, 1;

15, 1, 0, 0, 1, 0, 0, 0, 0, 1;

11, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1;

23, 1, 1, 1, 0, 1, 0, 0, 0, 0, 0, 1;

13, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1;

21, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1;

...

Cf. A158221, A051731, A158901

Sequence in context: A130026 A113287 A096798 this_sequence A137587 A137639 A113288

Adjacent sequences: A158899 A158900 A158901 this_sequence A158903 A158904 A158905

nonn,tabl

Gary W. Adamson & Mats Granvik (qntmpkt(AT)yahoo.com), Mar 29 2009