%I #6 Apr 24 2021 08:51:51
%S 0,6,34,1242,28216,4092246,318984080,159130979900,43562979789278,
%T 76371552378548280,73355302704339455588
%N Number of white-square subarrays of (n+2) X (n+2) 0..3 arrays x(i,j) with each element diagonally or antidiagonally next to at least one element with value (x(i,j)+1) mod 4, no adjacent elements equal, and upper left element zero.
%C Diagonal of A230940.
%e Some solutions for n=4
%e ..0..x..2..x..0..x....0..x..0..x..0..x....0..x..2..x..2..x....0..x..2..x..0..x
%e ..x..1..x..3..x..1....x..1..x..1..x..3....x..1..x..3..x..1....x..1..x..3..x..1
%e ..0..x..2..x..2..x....2..x..2..x..0..x....0..x..2..x..0..x....0..x..2..x..2..x
%e ..x..3..x..1..x..1....x..3..x..1..x..3....x..3..x..3..x..1....x..1..x..1..x..1
%e ..2..x..0..x..2..x....0..x..2..x..0..x....2..x..0..x..2..x....0..x..0..x..0..x
%e ..x..3..x..3..x..1....x..1..x..1..x..3....x..1..x..3..x..1....x..3..x..3..x..3
%Y Cf. A230940.
%K nonn
%O 1,2
%A _R. H. Hardin_, Nov 01 2013