%I #6 May 03 2020 15:38:07
%S 0,4,48,466,4444,46701,467104,4833331,52153064,578390147,6590059758,
%T 79294094586,1014580074422,13933640462306,204079081718026
%N Number of n X n 0..1 arrays with every element equal to 1, 2 or 3 king-move adjacent elements, with upper left element zero.
%C Diagonal of A297823.
%e Some solutions for n=6
%e ..0..1..0..1..1..0. .0..1..1..0..0..1. .0..0..1..0..0..1. .0..0..1..0..1..0
%e ..0..1..0..1..0..1. .1..0..0..1..1..0. .0..1..0..1..0..1. .1..1..0..1..0..1
%e ..1..1..0..1..0..0. .0..1..1..0..0..0. .0..1..0..1..0..1. .0..1..0..1..0..1
%e ..0..1..0..1..1..1. .1..0..0..1..1..1. .1..1..0..1..0..0. .1..0..0..1..0..0
%e ..0..1..0..0..0..0. .0..1..1..0..0..0. .0..1..0..1..0..1. .1..1..1..1..0..1
%e ..0..0..1..1..1..1. .0..0..1..0..1..1. .1..0..0..1..0..1. .0..0..0..0..1..1
%Y Cf. A297823.
%K nonn
%O 1,2
%A _R. H. Hardin_, Jan 06 2018
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