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Number of n X n 0..2n-2 arrays with upper left zero and lower right 2n-2 and each element differing from its horizontal and antidiagonal neighbors by one or two.
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%I #5 Dec 18 2015 18:18:54

%S 1,3,550,398508,2002867877,49094408347776,6109458550119472926,

%T 3756191694523776480082260,11421616015549105186265908485988

%N Number of n X n 0..2n-2 arrays with upper left zero and lower right 2n-2 and each element differing from its horizontal and antidiagonal neighbors by one or two.

%C Diagonal of A265466.

%e Some solutions for n=3

%e ..0..2..4....0..2..1....0..2..3....0..2..3....0..1..2....0..2..0....0..2..3

%e ..3..2..1....3..2..0....3..2..1....0..2..4....2..3..4....0..2..0....3..2..0

%e ..1..3..4....1..2..4....1..3..4....3..2..4....2..3..4....0..2..4....4..2..4

%Y Cf. A265466.

%K nonn

%O 1,2

%A _R. H. Hardin_, Dec 09 2015