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%I #7 Apr 20 2020 00:05:57
%S 1,3,8,20,63,453,6311,92889,1847358,65801890,3339677315,218906752065,
%T 21593578996507,3271858745091063,693762002728416501,
%U 208397398216895893003,93110263365139995537485
%N Number of n X n 0..1 arrays with every element equal to 0, 1, 4 or 6 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero.
%C Diagonal of A302680.
%H R. H. Hardin, <a href="/A302674/b302674.txt">Table of n, a(n) for n = 1..20</a>
%e Some solutions for n=5
%e ..0..1..0..1..0. .0..1..0..0..0. .0..0..0..1..0. .0..1..1..1..0
%e ..0..1..0..1..0. .0..1..0..1..0. .0..1..0..1..0. .0..1..0..1..0
%e ..0..1..0..1..0. .0..1..0..1..0. .0..1..0..1..0. .0..0..0..1..0
%e ..0..1..0..1..0. .0..1..0..1..0. .0..1..0..0..0. .0..1..0..1..0
%e ..0..1..0..0..0. .0..1..0..1..0. .0..1..0..1..0. .0..1..0..1..0
%Y Cf. A302680.
%K nonn
%O 1,2
%A _R. H. Hardin_, Apr 11 2018
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