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%I #4 Aug 06 2018 11:48:44
%S 2,6,10,20,42,89,190,407,873,1874,4024,8642,18561,39866,85627,183917,
%T 395034,848492,1822474,3914489,8407926,18059375,38789713,83316386,
%U 178955184,384377666,825604417,1773314930,3808901427,8181135701
%N Number of nX2 0..1 arrays with every element unequal to 0, 1 or 2 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero.
%C Column 2 of A317764.
%H R. H. Hardin, <a href="/A317759/b317759.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 2*a(n-1) +a(n-2) -a(n-3) -a(n-4) for n>6
%e Some solutions for n=5
%e ..0..0. .0..1. .0..1. .0..0. .0..0. .0..0. .0..0. .0..0. .0..1. .0..0
%e ..1..1. .1..1. .1..1. .1..1. .1..1. .0..0. .0..1. .0..1. .1..1. .0..0
%e ..1..1. .0..0. .1..1. .1..0. .1..1. .0..0. .1..1. .1..1. .0..0. .1..1
%e ..0..0. .0..0. .1..1. .0..0. .1..1. .0..1. .0..0. .1..1. .0..1. .1..1
%e ..0..0. .1..1. .1..0. .0..1. .0..0. .1..1. .0..1. .1..0. .1..1. .0..0
%Y Cf. A317764.
%K nonn
%O 1,1
%A _R. H. Hardin_, Aug 06 2018
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