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A268734
Number of n X n binary arrays with some 1 horizontally or vertically adjacent to some other 1 exactly once.
1
0, 4, 80, 2876, 200204, 29134076, 9039552112, 6084192150856, 8965720251221240, 29122359898196696856, 209490003763160695865576, 3348908247850171650090422060, 119286836904111393911302107179212
OFFSET
1,2
COMMENTS
Diagonal of A268740.
LINKS
EXAMPLE
Some solutions for n=4
..0..0..0..0. .1..0..1..0. .0..1..0..1. .0..0..1..0. .0..0..1..0
..0..0..0..1. .1..0..0..1. .0..0..1..0. .1..0..1..0. .0..0..0..0
..1..0..0..0. .0..1..0..0. .0..0..1..0. .0..0..0..0. .0..0..1..0
..1..0..0..0. .0..0..0..0. .0..1..0..1. .0..0..0..0. .1..1..0..0
CROSSREFS
Cf. A268740.
Sequence in context: A189791 A057875 A187543 * A012824 A012057 A214298
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 12 2016
STATUS
approved