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A316688 Number of nX3 0..1 arrays with every element unequal to 0, 1, 2, 6, 7 or 8 king-move adjacent elements, with upper left element zero. 1

%I

%S 4,3,8,9,21,42,81,165,330,657,1317,2634,5265,10533,21066,42129,84261,

%T 168522,337041,674085,1348170,2696337,5392677,10785354,21570705,

%U 43141413,86282826,172565649,345131301,690262602,1380525201,2761050405,5522100810

%N Number of nX3 0..1 arrays with every element unequal to 0, 1, 2, 6, 7 or 8 king-move adjacent elements, with upper left element zero.

%C Column 3 of A316693.

%H R. H. Hardin, <a href="/A316688/b316688.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = a(n-1) +a(n-2) +2*a(n-3) for n>6

%e Some solutions for n=5

%e ..0..0..0. .0..0..0. .0..0..0. .0..0..0. .0..0..0. .0..0..0. .0..0..0

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

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

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

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

%Y Cf. A316693.

%K nonn

%O 1,1

%A _R. H. Hardin_, Jul 10 2018

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Last modified January 24 06:43 EST 2021. Contains 340398 sequences. (Running on oeis4.)