Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #6 Mar 31 2012 12:37:32
%S 35,5558,6028871,44678808183,2261599192647037,781910030615896210474,
%T 1846356382998737252290206762,29777644269614247388351983235258241,
%U 3280051134759806457403130482690269897360711
%N Half the number of (n+1)X(n+1) 0..2 arrays with every 2X2 subblock having two or three distinct clockwise edge differences
%C Diagonal of A210276
%H R. H. Hardin, <a href="/A210268/b210268.txt">Table of n, a(n) for n = 1..11</a>
%e Some solutions for n=4
%e ..0..2..2..0..0....2..2..1..2..2....2..1..0..2..1....0..0..0..1..2
%e ..0..1..0..2..1....2..1..2..1..1....2..1..2..2..1....1..0..2..1..0
%e ..1..1..2..0..0....1..2..1..1..2....2..0..2..0..0....2..2..2..0..0
%e ..2..0..1..1..0....1..1..0..1..2....0..0..2..1..2....2..0..1..0..1
%e ..1..1..1..2..1....1..2..0..1..2....0..1..2..0..2....1..0..1..0..1
%K nonn
%O 1,1
%A _R. H. Hardin_ Mar 19 2012