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%I #10 Sep 12 2018 15:08:35
%S 3,20,126,780,4808,29608,182288,1122240,6908896,42533440,261849728,
%T 1612032128,9924194048,61096565760,376130326016,2315580595200,
%U 14255467112448,87761291061248,540287045521408,3326182739886080
%N Number of n X 4 binary arrays with top left element equal to 1 and no two ones adjacent horizontally or antidiagonally.
%H R. H. Hardin, <a href="/A228750/b228750.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 8*a(n-1) - 12*a(n-2) + 4*a(n-3).
%F Empirical g.f.: x*(3 - 4*x + 2*x^2) / (1 - 8*x + 12*x^2 - 4*x^3). - _Colin Barker_, Sep 12 2018
%e Some solutions for n=4:
%e ..1..0..1..0....1..0..0..0....1..0..0..0....1..0..0..0....1..0..1..0
%e ..0..0..1..0....1..0..1..0....0..1..0..1....0..1..0..0....0..0..1..0
%e ..1..0..0..1....1..0..0..1....0..1..0..1....0..0..1..0....1..0..1..0
%e ..0..0..0..0....0..1..0..1....0..1..0..1....1..0..0..1....0..0..1..0
%Y Column 4 of A228754.
%K nonn
%O 1,1
%A _R. H. Hardin_, Sep 02 2013
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