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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
OFFSET
1,4
COMMENTS
Diagonal of A303636.
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
KEYWORD
nonn
AUTHOR
R. H. Hardin, Apr 27 2018
STATUS
approved