%I #4 Nov 03 2013 05:59:20
%S 6,242,8374,3160834,584293702,1576885946694,2042677948725090,
%T 36336036129055657778
%N Number of (n+3)X(n+3) 0..3 black square subarrays x(i,j) with each element diagonally or antidiagonally next to at least one element with value (x(i,j)+1) mod 4, and upper left element zero
%C Diagonal of A231023
%e Some solutions for n=2
%e ..x..0..x..1..x....x..0..x..2..x....x..0..x..3..x....x..0..x..0..x
%e ..1..x..3..x..2....2..x..1..x..3....1..x..0..x..2....3..x..1..x..0
%e ..x..2..x..3..x....x..3..x..0..x....x..2..x..1..x....x..2..x..1..x
%e ..1..x..0..x..2....0..x..2..x..3....1..x..3..x..1....1..x..0..x..2
%e ..x..3..x..1..x....x..1..x..2..x....x..0..x..2..x....x..3..x..3..x
%K nonn
%O 1,1
%A _R. H. Hardin_, Nov 03 2013