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A268623 Number of n X 3 0..2 arrays with some element plus some horizontally or vertically adjacent neighbor totalling two no more than once.

%I A268623 #8 Jan 14 2019 09:01:28
%S A268623 24,174,1086,6300,34890,187224,982086,5063964,25764066,129678528,
%T A268623 646978302,3204131172,15769455258,77195600520,376136512950,
%U A268623 1825265294892,8825528262738,42536536932432,204425809550958,979908028544244
%N A268623 Number of n X 3 0..2 arrays with some element plus some horizontally or vertically adjacent neighbor totalling two no more than once.
%H A268623 R. H. Hardin, <a href="/A268623/b268623.txt">Table of n, a(n) for n = 1..210</a>
%F A268623 Empirical: a(n) = 10*a(n-1) - 29*a(n-2) + 20*a(n-3) - 4*a(n-4).
%F A268623 Empirical g.f.: 6*x*(4 - 11*x + 7*x^2 + x^3) / (1 - 5*x + 2*x^2)^2. - _Colin Barker_, Jan 14 2019
%e A268623 Some solutions for n=6:
%e A268623 ..0..0..1. .0..0..0. .2..2..1. .1..0..1. .1..2..1. .1..0..1. .1..0..1
%e A268623 ..0..1..2. .1..0..0. .0..1..2. .0..0..0. .0..1..2. .0..1..2. .0..0..0
%e A268623 ..2..2..2. .0..1..0. .1..0..1. .1..0..0. .0..0..1. .1..0..1. .1..1..0
%e A268623 ..1..2..2. .1..2..1. .0..1..0. .0..0..1. .1..0..0. .2..1..0. .0..0..0
%e A268623 ..2..1..2. .0..1..0. .1..0..1. .2..1..0. .2..2..1. .2..0..1. .1..0..0
%e A268623 ..1..2..2. .0..1..0. .0..1..2. .1..0..1. .1..2..2. .2..1..2. .2..1..0
%Y A268623 Column 3 of A268628.
%K A268623 nonn
%O A268623 1,1
%A A268623 _R. H. Hardin_, Feb 09 2016