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%I #7 Apr 19 2020 23:45:00
%S 3,60,2016,136080,18852912,5712070032,3870355944960,5963413766987592,
%T 21098726553552173712,172587783760354579099176,
%U 3279749300107885644432555744,145303202175464965696103410891992
%N Number of n X n 0..2 arrays with some element plus some horizontally or antidiagonally adjacent neighbor totalling two not more than once.
%C Diagonal of A268971.
%H R. H. Hardin, <a href="/A268964/b268964.txt">Table of n, a(n) for n = 1..15</a>
%e Some solutions for n=4
%e ..0..1..0..1. .1..0..0..1. .1..2..0..0. .2..1..2..2. .0..1..0..0
%e ..0..1..0..0. .1..0..2..1. .1..0..1..2. .2..1..2..1. .2..1..1..0
%e ..2..1..0..0. .1..2..2..1. .1..0..1..2. .2..2..2..1. .0..0..1..0
%e ..2..1..1..0. .2..2..2..2. .1..0..1..0. .1..1..2..1. .0..0..1..0
%Y Cf. A268971.
%K nonn
%O 1,1
%A _R. H. Hardin_, Feb 16 2016
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