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

0,2

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, ...).

Links

Table of n, a(n) for n=0..77.

Example

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.

Sequence in context: A159919 A310929 A310930 * A088744 A168074 A061891

Adjacent sequences: A131429 A131430 A131431 * A131433 A131434 A131435

Keyword

nonn,tabl

Author

Gary W. Adamson, Jul 10 2007

Extensions

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

Status

approved