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 A211052 1/3 the number of n X n 0..2 symmetric matrices with every element equal to one, two or three horizontal and vertical neighbors 1

%I #6 Dec 18 2015 18:18:07

%S 0,1,9,239,14669,2313041,915560157,915512113455,2309733753013069,

%T 14705975948890342013,236286306641789616616527,

%U 9580759647090339471565196845,980341335177418943590433413869387

%N 1/3 the number of n X n 0..2 symmetric matrices with every element equal to one, two or three horizontal and vertical neighbors

%H R. H. Hardin, <a href="/A211052/b211052.txt">Table of n, a(n) for n = 1..14</a>

%e Some solutions for n=4

%e ..0..0..1..0....1..1..2..2....1..1..0..0....2..2..0..2....0..0..1..1

%e ..0..1..1..0....1..1..2..1....1..1..1..1....2..2..0..2....0..0..2..2

%e ..1..1..1..1....2..2..1..1....0..1..1..0....0..0..2..2....1..2..2..2

%e ..0..0..1..1....2..1..1..1....0..1..0..0....2..2..2..2....1..2..2..2

%K nonn

%O 1,3

%A _R. H. Hardin_ Mar 30 2012

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Last modified June 16 16:46 EDT 2024. Contains 373432 sequences. (Running on oeis4.)