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%I #7 Apr 19 2020 23:54:46
%S 1,4,24,207,5570,261939,20599895,3819208252,1400212345305,
%T 937962844219314,1312275096984570369,3708386833907642906568,
%U 20177474743877943669370721,220442917573207336661039688056
%N Number of n X n 0..1 arrays with every 1 horizontally or antidiagonally adjacent to 1 neighboring 1's.
%C Diagonal of A297224.
%H R. H. Hardin, <a href="/A297218/b297218.txt">Table of n, a(n) for n = 1..23</a>
%e Some solutions for n=5
%e ..1..1..0..0..0. .0..0..1..1..0. .1..1..0..0..0. .0..1..1..0..0
%e ..0..0..0..0..0. .0..0..0..1..1. .0..1..1..0..0. .0..0..0..1..1
%e ..0..1..1..0..0. .1..1..0..0..0. .0..0..1..1..0. .0..0..0..0..0
%e ..0..0..0..1..1. .0..0..0..1..1. .0..0..0..1..1. .0..0..1..0..1
%e ..0..0..0..0..0. .1..1..0..0..0. .1..1..0..0..0. .0..1..0..1..0
%Y Cf. A297224.
%K nonn
%O 1,2
%A _R. H. Hardin_, Dec 27 2017
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