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%I #6 Sep 16 2020 19:06:41
%S 0,1,0,4,20,394,7538,501126,43679228,8515657512,2784504147786
%N Number of n X n 0..1 arrays with every element unequal to 2 or 3 horizontally or vertically adjacent elements, with upper left element zero.
%C Diagonal of A303636.
%e Some solutions for n=5
%e ..0..1..0..0..1. .0..1..0..0..1. .0..1..0..1..0. .0..1..0..1..0
%e ..1..0..1..1..0. .1..0..1..1..0. .1..1..0..0..1. .1..0..0..1..1
%e ..1..0..0..0..1. .0..0..1..1..0. .0..0..1..0..1. .0..1..1..0..0
%e ..0..1..1..0..1. .1..1..0..0..1. .1..0..1..1..0. .1..0..0..1..1
%e ..1..0..0..1..0. .0..1..0..1..0. .0..1..0..0..1. .0..1..0..1..0
%Y Cf. A303636.
%K nonn
%O 1,4
%A _R. H. Hardin_, Apr 27 2018
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