A131432 Triangle read by rows: (A000012 * A131431) + (A131431 * A000012) - A000012 as infinite lower triangular matrices.

1, 4, 7, 7, 10, 13, 10, 13, 16, 19, 13, 16, 19, 22, 25, 16, 19, 22, 25, 28, 31, 19, 22, 25, 28, 31, 34, 37, 22, 25, 28, 31, 34, 37, 40, 43, 25, 28, 31, 34, 37, 40, 43, 46, 49, 28, 31, 34, 37, 40, 43, 46, 49, 52, 55, 31, 34, 37, 40, 43, 46, 49, 52, 55, 58, 61, 34, 37, 40, 43, 46, 49, 52, 55, 58, 61, 64, 67

Offset: 0

Author

Gary W. Adamson, Jul 10 2007

Keywords

• nonn
• tabl

Comments

Left border = A016777, (1, 4, 7, 10, 13, ...).

Right border = A016921: (1, 7, 13, 19, 25, ...).

Row sums = A051682, 11-gonal numbers: (1, 11, 30, 58, 95, ...).

Examples

			First few rows of the triangle:
   1;
   4,  7;
   7, 10, 13;
  10, 13, 16, 19;
  13, 16, 19, 22, 25;
  16, 19, 22, 25, 28, 31;
  19, 22, 25, 28, 31, 34, 37;
  ...
		

Crossrefs

Cf. A016777, A051682, A131431, A016921.

Extensions

a(28) ff. corrected and more terms from Georg Fischer, Jun 05 2023