A131781 2*A046854 - A000012 (signed by columns + - + -, ...).

1, 3, 1, 1, 3, 1, 3, 3, 3, 1, 1, 5, 5, 3, 1, 3, 5, 7, 7, 3, 1, 1, 7, 11, 9, 9, 3, 1, 3, 7, 13, 19, 11, 11, 3, 1, 1, 9, 19, 21, 29, 13, 13, 3, 1, 3, 9, 21, 39, 31, 41, 15, 15, 3, 1

Offset

1,2

Comments

Row sums = A131780: (1, 4, 5, 10, 15, 26, 41, ...), a sequence with a(n)/a(n-1) tending to phi.

A131779 is a companion triangle, same row sums.

Links

Table of n, a(n) for n=1..55.

Example

First few rows of the triangle:
  1;
  3,  1;
  1,  3,  1;
  3,  3,  3,  1;
  1,  5,  5,  3,  1;
  3,  5,  7,  7,  3,  1;
  1,  7, 11,  9,  9,  3,  1;
  3,  7, 13, 19, 11, 11,  3,  1;
  ...

Crossrefs

Cf. A131779, A131780, A046854, A000012.

Sequence in context: A131775 A218825 A035691 * A082465 A226856 A131327

Adjacent sequences: A131778 A131779 A131780 * A131782 A131783 A131784

Keyword

nonn,tabl

Author

Gary W. Adamson, Jul 14 2007

Status

approved