A303630 Number of n X n 0..1 arrays with every element unequal to 2 or 3 horizontally or vertically adjacent elements, with upper left element zero.

0, 1, 0, 4, 20, 394, 7538, 501126, 43679228, 8515657512, 2784504147786

Offset

1,4

Comments

Diagonal of A303636.

Links

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

Example

Some solutions for n=5
..0..1..0..0..1. .0..1..0..0..1. .0..1..0..1..0. .0..1..0..1..0
..1..0..1..1..0. .1..0..1..1..0. .1..1..0..0..1. .1..0..0..1..1
..1..0..0..0..1. .0..0..1..1..0. .0..0..1..0..1. .0..1..1..0..0
..0..1..1..0..1. .1..1..0..0..1. .1..0..1..1..0. .1..0..0..1..1
..1..0..0..1..0. .0..1..0..1..0. .0..1..0..0..1. .0..1..0..1..0

Crossrefs

Cf. A303636.

Sequence in context: A227005 A054465 A118713 * A257547 A160703 A132511

Adjacent sequences: A303627 A303628 A303629 * A303631 A303632 A303633

Keyword

nonn

Author

R. H. Hardin, Apr 27 2018

Status

approved