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%I #11 Oct 13 2018 09:23:07
%S 46,226,1108,5446,26794,131896,649450,3198322,15751828,77581198,
%T 382112002,1882042264,9269800642,45657552106,224882405380,
%U 1107640064854,5455593492922,26871099434488,132351514215994,651887143644034
%N Number of (n+1) X (1+1) 0..3 arrays with every 2 X 2 subblock having the absolute values of all six edge and diagonal differences no larger than 1.
%H R. H. Hardin, <a href="/A234154/b234154.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 7*a(n-1) - 9*a(n-2) - 6*a(n-3).
%F Empirical g.f.: 2*x*(23 - 48*x - 30*x^2) / (1 - 7*x + 9*x^2 + 6*x^3). - _Colin Barker_, Oct 13 2018
%e Some solutions for n=5:
%e 3 3 1 1 2 2 1 2 3 3 3 2 0 1 1 2 2 2 2 2
%e 2 3 1 0 1 1 2 2 2 3 3 3 0 0 1 2 1 1 2 1
%e 2 2 0 1 1 0 2 3 2 3 2 3 1 1 2 2 1 2 1 2
%e 2 1 1 1 1 1 3 3 2 2 3 3 0 0 2 2 2 1 2 2
%e 1 1 1 1 1 1 3 2 2 3 2 2 1 1 2 2 2 1 1 2
%e 1 0 1 2 2 1 2 2 3 2 3 3 0 0 2 3 1 2 2 2
%Y Column 1 of A234161.
%K nonn
%O 1,1
%A _R. H. Hardin_, Dec 20 2013
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