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Number of n X n 0..2 arrays with the sum of the absolute differences of each element with its horizontal and vertical neighbors equal to the number of neighbors.
1

%I #6 Dec 18 2015 18:18:54

%S 3,12,68,664,13672,560512,51483264,8726974464,3316077264896,

%T 2260633288966144,3463290521072435200,9453965541320232534016,

%U 58047351977461819763589120,633980080610711649347287646208

%N Number of n X n 0..2 arrays with the sum of the absolute differences of each element with its horizontal and vertical neighbors equal to the number of neighbors.

%C Diagonal of A265887.

%H R. H. Hardin, <a href="/A265886/b265886.txt">Table of n, a(n) for n = 1..18</a>

%e Some solutions for n=4

%e ..2..1..2..2....0..0..1..0....1..2..1..0....1..2..1..2....2..1..0..1

%e ..1..2..0..0....2..2..0..1....2..1..2..1....0..1..2..1....1..2..1..2

%e ..2..2..0..1....1..2..0..2....1..2..1..0....1..2..1..0....2..1..2..1

%e ..0..0..1..2....0..1..0..2....0..1..0..1....2..1..0..1....1..2..1..2

%Y Cf. A265887.

%K nonn

%O 1,1

%A _R. H. Hardin_, Dec 17 2015