%I #6 Dec 18 2015 18:17:59

%S 0,4,80,5956,6709692,47309058644,2168622256129656,

%T 736756458623041306372

%N Number of n X n 0..3 arrays with every element neighboring horizontally or vertically both a 0 and a 1, and 2 introduced before 3 in row major order

%C Diagonal of A204301

%e Some solutions for n=4

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

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

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

%e ..0..1..1..0....0..1..1..1....0..1..1..1....0..0..1..1....3..0..1..1

%K nonn

%O 1,2

%A _R. H. Hardin_ Jan 14 2012