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%I #11 Sep 11 2018 09:45:51
%S 2,3,12,29,88,239,684,1909,5392,15143,42644,119933,337512,949535,
%T 2671740,7517061,21150272,59508247,167433188,471090573,1325464216,
%U 3729333775,10492879052,29522830997,83065631600,233713998087,657579228980
%N Number of n X 3 binary arrays with top left value 1 and no two ones adjacent horizontally, vertically, diagonally or antidiagonally.
%H R. H. Hardin, <a href="/A228501/b228501.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 2*a(n-1) + 3*a(n-2) - 2*a(n-3).
%F Empirical g.f.: x*(2 - x) / (1 - 2*x - 3*x^2 + 2*x^3). - _Colin Barker_, Sep 11 2018
%e Some solutions for n=4:
%e ..1..0..1....1..0..0....1..0..1....1..0..0....1..0..0....1..0..1....1..0..0
%e ..0..0..0....0..0..1....0..0..0....0..0..0....0..0..0....0..0..0....0..0..1
%e ..0..0..1....0..0..0....0..0..1....1..0..1....0..0..0....0..1..0....0..0..0
%e ..0..0..0....1..0..0....1..0..0....0..0..0....0..0..1....0..0..0....0..0..0
%Y Column 3 of A228506.
%K nonn
%O 1,1
%A _R. H. Hardin_, Aug 23 2013
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