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A221287 Equals two maps: number of n X n binary arrays indicating the locations of corresponding elements equal to exactly two of their horizontal and antidiagonal neighbors in a random 0..3 n X n array.

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%I A221287 #7 Jul 23 2025 01:48:53
%S A221287 1,4,92,9107,4983598,10344276279
%N A221287 Equals two maps: number of n X n binary arrays indicating the locations of corresponding elements equal to exactly two of their horizontal and antidiagonal neighbors in a random 0..3 n X n array.
%C A221287 Diagonal of A221290
%e A221287 Some solutions for n=3
%e A221287 ..0..0..0....0..0..1....0..1..0....0..0..0....0..0..1....0..1..1....0..0..1
%e A221287 ..1..1..0....1..0..1....0..1..0....1..0..1....0..1..0....0..1..1....1..0..1
%e A221287 ..1..1..0....1..1..0....1..1..0....1..0..0....1..1..0....0..1..0....1..0..0
%K A221287 nonn
%O A221287 1,2
%A A221287 _R. H. Hardin_ Jan 09 2013

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