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A268632
Number of n X n 0..2 arrays with some element plus some horizontally or vertically adjacent neighbor totalling two exactly once.
1
0, 24, 840, 47640, 5419992, 1328460312, 725187096504, 897937832100888, 2550310193527246056, 16737195174968513278656, 255111495114527014241534160, 9064348272085612349020943764248, 752834148761621410865592159869765856
OFFSET
1,2
COMMENTS
Diagonal of A268639.
LINKS
EXAMPLE
Some solutions for n=4
..0..0..0..1. .2..2..0..1. .0..0..0..0. .0..0..0..0. .1..0..1..0
..1..0..0..0. .1..2..1..2. .0..1..0..0. .1..0..0..0. .2..1..2..0
..0..1..0..1. .2..1..2..1. .1..0..1..0. .1..0..0..0. .1..0..1..0
..0..0..0..2. .1..0..1..0. .2..0..0..0. .2..1..0..1. .0..0..0..0
CROSSREFS
Cf. A268639.
Sequence in context: A265884 A204559 A078522 * A208792 A195130 A005149
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 09 2016
STATUS
approved