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A204625 Number of (n+1) X 4 0..2 arrays with every 2 X 2 subblock having unequal diagonal elements or unequal antidiagonal elements, and new values 0..2 introduced in row major order.

%I A204625 #8 Jun 07 2018 14:24:15
%S A204625 768,43734,2490558,141832254,8077061502,459972403614,26194503047262,
%T A204625 1491724252385406,84950695233299262,4837771196037723486,
%U A204625 275501337345598245918,15689246928705157494846,893471050128160321852158
%N A204625 Number of (n+1) X 4 0..2 arrays with every 2 X 2 subblock having unequal diagonal elements or unequal antidiagonal elements, and new values 0..2 introduced in row major order.
%C A204625 Column 3 of A204630.
%H A204625 R. H. Hardin, <a href="/A204625/b204625.txt">Table of n, a(n) for n = 1..210</a>
%F A204625 Empirical: a(n) = 60*a(n-1) - 175*a(n-2) + 68*a(n-3).
%F A204625 Empirical g.f.: 6*x*(128 - 391*x + 153*x^2) / (1 - 60*x + 175*x^2 - 68*x^3). - _Colin Barker_, Jun 07 2018
%e A204625 Some solutions for n=3:
%e A204625 ..0..1..2..1....0..0..0..0....0..1..0..2....0..0..0..0....0..0..0..1
%e A204625 ..2..2..0..0....1..0..1..0....1..2..2..1....1..0..1..0....2..0..1..1
%e A204625 ..0..2..2..0....2..1..1..0....1..0..1..1....2..2..1..2....0..0..1..2
%e A204625 ..0..1..0..1....2..0..0..0....0..0..2..0....0..0..2..0....2..0..0..1
%Y A204625 Cf. A204630.
%K A204625 nonn
%O A204625 1,1
%A A204625 _R. H. Hardin_, Jan 17 2012