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A209725 1/4 the number of (n+1) X 7 0..2 arrays with every 2 X 2 subblock having distinct clockwise edge differences.

%I A209725 #8 Jul 12 2018 09:15:35
%S A209725 12,13,14,16,18,22,26,34,42,58,74,106,138,202,266,394,522,778,1034,
%T A209725 1546,2058,3082,4106,6154,8202,12298,16394,24586,32778,49162,65546,
%U A209725 98314,131082,196618,262154,393226,524298,786442,1048586,1572874,2097162
%N A209725 1/4 the number of (n+1) X 7 0..2 arrays with every 2 X 2 subblock having distinct clockwise edge differences.
%C A209725 Column 6 of A209727.
%H A209725 R. H. Hardin, <a href="/A209725/b209725.txt">Table of n, a(n) for n = 1..210</a>
%F A209725 Empirical: a(n) = a(n-1) + 2*a(n-2) - 2*a(n-3).
%F A209725 Conjectures from _Colin Barker_, Jul 12 2018: (Start)
%F A209725 G.f.: x*(12 + x - 23*x^2) / ((1 - x)*(1 - 2*x^2)).
%F A209725 a(n) = 3*2^(n/2 - 1) + 10 for n even.
%F A209725 a(n) = 2^((n + 1)/2) + 10 for n odd.
%F A209725 (End)
%e A209725 Some solutions for n=4:
%e A209725 ..1..0..1..0..1..0..1....2..0..2..0..1..0..2....0..1..0..1..0..1..0
%e A209725 ..0..2..0..2..0..2..0....1..2..1..2..0..2..1....2..0..2..0..2..0..2
%e A209725 ..1..0..1..0..1..0..1....2..0..2..0..1..0..2....0..1..0..1..0..1..0
%e A209725 ..0..2..0..2..0..2..0....1..2..1..2..0..2..1....2..0..2..0..2..0..2
%e A209725 ..1..0..1..0..1..0..1....2..0..2..0..1..0..2....0..1..0..1..0..1..0
%Y A209725 Cf. A209727.
%K A209725 nonn
%O A209725 1,1
%A A209725 _R. H. Hardin_, Mar 12 2012