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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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Diagonal of A268740. LINKS R. H. Hardin, Table of n, a(n) for n = 1..26 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 Adjacent sequences:  A268731 A268732 A268733 * A268735 A268736 A268737 KEYWORD nonn AUTHOR R. H. Hardin, Feb 12 2016 STATUS approved

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Last modified August 17 08:02 EDT 2022. Contains 356184 sequences. (Running on oeis4.)