A137679 Triangle read by rows, A000012 * A008284.

1, 2, 1, 3, 2, 1, 4, 4, 2, 1, 5, 6, 4, 2, 1, 6, 9, 7, 4, 2, 1, 7, 12, 11, 7, 4, 2, 1, 8, 16, 16, 12, 7, 4, 2, 1, 9, 20, 23, 18, 12, 7, 4, 2, 1, 10, 25, 31, 27, 19, 12, 7, 4, 2, 1, 11, 30, 41, 38, 29, 19, 12, 7, 4, 2, 1, 12, 36, 53, 53, 42, 30, 19, 12, 7, 4, 2, 1

Offset: 1

Author

Gary W. Adamson, Feb 05 2008

Keywords

• nonn
• tabl

Comments

Row sums = A026905: (1, 3, 6, 11, 18, 29, ...).

Rows tend to A000070 starting from the right: (1, 2, 4, 7, 12, 19, 30, ...).

Examples

			First few rows of the triangle:
  1;
  2,  1;
  3,  2,  1;
  4,  4,  2,  1;
  5,  6,  4,  2, 1;
  6,  9,  7,  4, 2, 1;
  7, 12, 11,  7, 4, 2, 1;
  8, 16, 16, 12, 7, 4, 2, 1;
  ...
		

Crossrefs

Cf. A000070, A008284, A026905.

Formula

A000012 * A008284 as infinite lower triangular matrices.

Extensions

a(38) = 20 corrected by Georg Fischer, May 29 2023