1,4

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

A168509 = A051731 * A101688

Triangle by rows, A101688 * A051731

First few rows of the triangle =

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;

8, 4, 3, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1;

8, 4, 3, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1;

9, 4, 3, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1;

...

Cf. A101688, A051731, A168509, A060831

Sequence in context: A073203 A073204 A034003 this_sequence A026835 A117975 A143258

Adjacent sequences: A168505 A168506 A168507 this_sequence A168509 A168510 A168511

nonn,tabl

Gary W. Adamson (qntmpkt(AT)yahoo.com), Nov 27 2009