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A206694 Number of n X 2 0..2 arrays avoiding the pattern z-2 z-1 z in any row or column.

%I A206694 #8 Feb 23 2018 09:52:07
%S A206694 9,81,676,5625,46656,386884,3207681,26594649,220492801,1828075536,
%T A206694 15156318321,125658906256,1041820324416,8637585806529,71613009227809,
%U A206694 593733388556025,4922560027477764,40812252925262329,338368649551172496
%N A206694 Number of n X 2 0..2 arrays avoiding the pattern z-2 z-1 z in any row or column.
%C A206694 Column 2 of A206700.
%H A206694 R. H. Hardin, <a href="/A206694/b206694.txt">Table of n, a(n) for n = 1..210</a>
%F A206694 Empirical: a(n) = 9*a(n-1) -3*a(n-2) -25*a(n-3) +9*a(n-4) +3*a(n-5) -a(n-6).
%F A206694 Empirical g.f.: x*(9 - 26*x^2 + 9*x^3 + 3*x^4 - x^5) / ((1 - 9*x + 6*x^2 - x^3)*(1 - 3*x^2 - x^3)). - _Colin Barker_, Feb 23 2018
%e A206694 Some solutions for n=4:
%e A206694 ..0..1....0..2....0..2....2..0....0..2....2..1....0..1....1..1....1..2....1..2
%e A206694 ..2..1....2..2....1..1....0..2....0..2....0..2....2..1....1..0....2..2....2..0
%e A206694 ..2..2....0..0....0..0....1..0....2..2....1..2....2..0....1..2....1..2....0..1
%e A206694 ..0..0....2..1....0..1....1..2....0..2....0..1....0..1....1..2....2..2....1..0
%Y A206694 Cf. A206700.
%K A206694 nonn
%O A206694 1,1
%A A206694 _R. H. Hardin_, Feb 11 2012