1,3

Row sums = A143152: (1, 3, 4, 5, 6, 8, 8, 7, 7, 10, 12, 12, 14, 12,

Triangle read by rows, A051731 * (A020639 * 0^(n-k)), 1<=k<=n; where A020639 = Lpf(n): (1, 2, 3, 2, 5, 2, 7, 2, 3, 2,...). By rows, least prime factors of the divisors of n, where the divisors of n are recorded in triangle A127093.

First few rows of the triangle are:

1;

1, 2;

1, 0, 3;

1, 2, 0, 2;

1, 0, 0, 0, 5;

1, 2, 3, 0, 0, 2;

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

1, 2, 0, 2, 0, 0, 0, 2;

1, 0, 3, 0, 0, 0, 0, 0, 3;

1, 2, 0, 0, 5, 0, 0, 0, 0, 2;

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

...

Row 12 = (1, 2, 3, 2, 0, 2, 0, 0, 0, 0, 0, 2) since the divisors of 12 are shown in row 12 of triangle A127093: (1, 2, 3, 4, 0, 6, 0, 0, 0, 0, 0, 12).

Lpf of these terms = row 12 of A143152.

Cf. A020639, A127093, A143152.

Adjacent sequences: A143148 A143149 A143150 this_sequence A143152 A143153 A143154

Sequence in context: A029293 A029312 A143256 this_sequence A130106 A127093 A141543

nonn,tabl

Gary W. Adamson & Mats O. Granvik (qntmpkt(AT)yahoo.com), Jul 27 2008