%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