A168508 - OEIS

A168508

Triangle read by rows: A101688 * A051731.

1, 1, 1, 2, 1, 1, 2, 1, 1, 1, 3, 1, 1, 1, 1, 3, 2, 1, 1, 1, 1, 4, 2, 1, 1, 1, 1, 1, 4, 2, 1, 1, 1, 1, 1, 1, 5, 2, 2, 1, 1, 1, 1, 1, 1, 5, 3, 2, 1, 1, 1, 1, 1, 1, 1, 6, 3, 2, 1, 1, 1, 1, 1, 1, 1, 1, 6, 3, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 7, 3, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 7, 4, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1

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OFFSET

1,4

COMMENTS

More precisely, form the product of the lower triangular matrix T defined in A101688 and the lower triangular matrix T defined in A051731. - N. J. A. Sloane, Dec 05 2020

Row sums = A060831: (1, 2, 4, 5, 7, 9, 11, 12, 15,...).

A168509 = A051731 * A101688

LINKS

Table of n, a(n) for n=1..105.

EXAMPLE

First few rows of the triangle =

1, 1;

2, 1, 1;

2, 1, 1, 1;

3, 1, 1, 1, 1;

3, 2, 1, 1, 1, 1;

4, 2, 1, 1, 1, 1, 1;