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%I #7 Oct 11 2018 09:02:03
%S 90,534,3004,17424,99380,572192,3277236,18825580,107963840,619734876,
%T 3555590252,20405232856,117085241588,671895102796,3855486448064,
%U 22124270945452,126955643098236,728515542322936,4180454758322084
%N Number of (n+1) X (2+1) 0..2 arrays with every 2 X 2 subblock having the sum of the squares of the edge differences equal to 2.
%H R. H. Hardin, <a href="/A233638/b233638.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 6*a(n-1) + 9*a(n-2) - 67*a(n-3) + 26*a(n-4) + 81*a(n-5) - 48*a(n-6) + 2*a(n-7).
%F Empirical g.f.: 2*x*(45 - 3*x - 505*x^2 + 312*x^3 + 619*x^4 - 405*x^5 + 17*x^6) / (1 - 6*x - 9*x^2 + 67*x^3 - 26*x^4 - 81*x^5 + 48*x^6 - 2*x^7). - _Colin Barker_, Oct 11 2018
%e Some solutions for n=5:
%e ..0..1..1....0..1..0....1..0..1....1..1..1....1..2..1....1..2..1....1..1..1
%e ..0..0..1....0..1..1....1..0..0....2..1..0....2..2..1....1..1..1....2..2..2
%e ..1..1..1....1..1..2....1..0..1....2..1..1....2..1..1....0..1..0....1..1..1
%e ..2..2..1....2..1..1....1..0..0....2..2..2....2..2..1....1..1..1....0..1..2
%e ..1..2..1....2..1..0....1..1..0....1..2..1....1..2..1....2..2..2....1..1..1
%e ..1..2..2....1..1..0....2..1..0....1..1..1....2..2..2....2..1..1....2..2..2
%Y Column 2 of A233644.
%K nonn
%O 1,1
%A _R. H. Hardin_, Dec 14 2013
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