A303720 Number of n X n 0..1 arrays with every element unequal to 0, 1, 2 or 3 king-move adjacent elements, with upper left element zero.

1, 8, 23, 84, 219, 569, 1476, 3614, 8730, 20886, 49351, 114833, 265877, 610405, 1396025, 3172297, 7195606, 16230944, 36563883, 82008735, 183813328, 410490052

Offset

1,2

Comments

Diagonal of A303727.

Links

Table of n, a(n) for n=1..22.

Example

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

Crossrefs

Cf. A303727.

Sequence in context: A208633 A036562 A320310 * A304414 A305949 A220973

Adjacent sequences: A303717 A303718 A303719 * A303721 A303722 A303723

Keyword

nonn

Author

R. H. Hardin, Apr 29 2018

Status

approved