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A268621
Number of n X n 0..2 arrays with some element plus some horizontally or vertically adjacent neighbor totaling two no more than once.
1
3, 42, 1086, 55452, 6000978, 1430057208, 767057092212, 938662461734076, 2643885168776274078, 17245474696462104041796, 261641272761781630830646332, 9262823664147270920479995625968, 767111588793900754143144516979246884
OFFSET
1,1
COMMENTS
Diagonal of A268628.
LINKS
EXAMPLE
Some solutions for n=4
..2..1..2..2. .0..0..0..0. .0..0..1..0. .2..1..0..0. .1..1..0..0
..1..0..1..2. .0..1..1..0. .0..0..0..1. .1..0..0..0. .2..2..1..0
..2..1..2..1. .1..0..0..1. .1..0..1..2. .0..1..0..0. .2..2..2..1
..2..2..2..0. .0..0..1..0. .0..1..2..2. .0..0..0..1. .2..2..1..0
CROSSREFS
Cf. A268628.
Sequence in context: A206820 A157542 A078601 * A218308 A195010 A333323
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 09 2016
STATUS
approved