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%I #6 May 03 2020 15:38:47
%S 0,1,4,15,2621,284344,76517448,58344517697,99045666327382,
%T 434103508383656941
%N Number of n X n 0..1 arrays with every element equal to 2, 3 or 4 king-move adjacent elements, with upper left element zero.
%C Diagonal of A297866.
%e Some solutions for n=5
%e ..0..0..0..1..1. .0..0..0..0..0. .0..0..1..1..1. .0..0..0..1..1
%e ..0..1..1..0..1. .0..1..1..1..0. .0..0..1..0..1. .1..0..0..1..1
%e ..0..0..1..0..0. .0..0..1..0..0. .0..1..1..0..0. .1..1..1..0..0
%e ..1..0..1..0..1. .0..0..1..0..0. .1..0..0..1..1. .0..0..1..1..0
%e ..1..1..1..1..1. .0..1..1..1..0. .1..1..0..0..1. .0..0..1..0..0
%Y Cf. A297866.
%K nonn
%O 1,3
%A _R. H. Hardin_, Jan 07 2018
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