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A274798 Number of n X 3 0..2 arrays with no element equal to any value at offset (-1,-2) (-2,-1) (0,-1) or (-1,0) and new values introduced in order 0..2.

%I A274798 #9 Jan 30 2019 15:51:13
%S A274798 2,8,30,112,420,1572,5888,22048,82568,309200,1157904,4336144,16238112,
%T A274798 60808896,227718752,852767104,3193464512,11958969152,44784259584,
%U A274798 167709263104,628042022016,2351908141824,8807486941952,32982506778880
%N A274798 Number of n X 3 0..2 arrays with no element equal to any value at offset (-1,-2) (-2,-1) (0,-1) or (-1,0) and new values introduced in order 0..2.
%H A274798 R. H. Hardin, <a href="/A274798/b274798.txt">Table of n, a(n) for n = 1..210</a>
%F A274798 Empirical: a(n) = 2*a(n-1) + 6*a(n-2) + 2*a(n-3).
%F A274798 Empirical g.f.: 2*x*(1 + x)^2 / (1 - 2*x - 6*x^2 - 2*x^3). - _Colin Barker_, Jan 30 2019
%e A274798 Some solutions for n=4:
%e A274798 ..0..1..2. .0..1..0. .0..1..0. .0..1..0. .0..1..0. .0..1..0. .0..1..0
%e A274798 ..2..0..1. .2..0..1. .1..0..2. .2..0..2. .2..0..2. .1..0..1. .1..2..1
%e A274798 ..0..1..0. .0..2..0. .0..2..0. .0..1..0. .0..2..0. .0..1..2. .2..1..0
%e A274798 ..1..0..2. .1..0..1. .1..0..1. .2..0..1. .1..0..2. .1..0..1. .0..2..1
%Y A274798 Column 3 of A274803.
%K A274798 nonn
%O A274798 1,1
%A A274798 _R. H. Hardin_, Jul 07 2016