A281556 Number of n X n 0..1 arrays with no element equal to more than two of its horizontal, diagonal or antidiagonal neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards.

0, 0, 68, 3374, 50510, 347316, 1818257, 8300608, 33449458, 124061416, 432930120

Offset

1,3

Comments

Diagonal of A281563.

Links

Table of n, a(n) for n=1..11.

Example

Some solutions for n=4
..0..0..0..1. .0..1..0..0. .0..1..1..0. .0..1..1..0. .0..0..0..1
..0..1..0..0. .1..0..1..1. .0..1..1..0. .1..0..1..0. .0..1..0..1
..0..1..1..1. .0..0..1..0. .0..0..0..0. .0..1..1..0. .0..0..0..1
..0..1..0..0. .1..1..0..0. .1..0..1..0. .1..0..1..1. .0..1..0..1

Crossrefs

Cf. A281563.

Sequence in context: A035729 A017731 A204298 * A093268 A231250 A159361

Adjacent sequences: A281553 A281554 A281555 * A281557 A281558 A281559

Keyword

nonn

Author

R. H. Hardin, Jan 24 2017

Status

approved