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%I #10 Jun 19 2022 01:20:28
%S 40,120,376,1200,3848,12360,39720,127664,410344,1318968,4239576,
%T 13627344,43802632,140795656,452562248,1454679760,4675805864,
%U 15029535096,48309731384,155282923376,499128966408,1604360091208,5156926316648
%N Number of (n+1) X (1+1) 0..4 arrays with every 2 X 2 subblock having its diagonal sum differing from its antidiagonal sum by 2, with no adjacent elements equal (constant-stress tilted 1 X 1 tilings).
%H R. H. Hardin, <a href="/A234914/b234914.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 4*a(n-1) - 2*a(n-2) - 2*a(n-3) + a(n-4).
%F Empirical g.f.: 8*x*(5 - 5*x - 3*x^2 + 2*x^3) / ((1 - x)*(1 - 3*x - x^2 + x^3)). - _Colin Barker_, Oct 16 2018
%e Some solutions for n=5:
%e 0 1 2 1 1 0 4 3 2 3 3 2 1 0 3 4 3 0 3 4
%e 1 4 1 2 4 1 3 4 1 0 4 1 4 1 0 3 4 3 4 3
%e 0 1 2 1 1 0 1 0 3 4 1 0 1 0 3 4 0 1 3 4
%e 4 3 3 4 0 1 2 3 1 0 3 4 4 1 4 3 1 4 1 0
%e 0 1 2 1 3 2 1 0 0 1 0 3 3 2 0 1 2 3 3 4
%e 3 2 3 0 2 3 4 1 4 3 3 4 0 1 4 3 1 0 2 1
%Y Column 1 of A234921.
%K nonn
%O 1,1
%A _R. H. Hardin_, Jan 01 2014
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