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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
0, 1, 0, 4, 20, 394, 7538, 501126, 43679228, 8515657512, 2784504147786 (list; graph; refs; listen; history; text; internal format)
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

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Last modified June 26 15:11 EDT 2022. Contains 354884 sequences. (Running on oeis4.)