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A274745 Number of n X 4 0..2 arrays with no element equal to any value at offset (-1,-2) (0,-1) or (-1,0) and new values introduced in order 0..2.

%I A274745 #8 Jan 30 2019 11:16:50
%S A274745 4,22,133,813,4967,30349,185435,1133025,6922887,42299477,258453699,
%T A274745 1579175897,9648910127,58955729261,360224933899,2201007512401,
%U A274745 13448358549783,82170708943301,502070597184787,3067697574952457
%N A274745 Number of n X 4 0..2 arrays with no element equal to any value at offset (-1,-2) (0,-1) or (-1,0) and new values introduced in order 0..2.
%H A274745 R. H. Hardin, <a href="/A274745/b274745.txt">Table of n, a(n) for n = 1..210</a>
%F A274745 Empirical: a(n) = 6*a(n-1) + a(n-2) - 2*a(n-3) for n>4.
%F A274745 Empirical g.f.: x*(1 - x)*(4 + 2*x - x^2) / (1 - 6*x - x^2 + 2*x^3). - _Colin Barker_, Jan 30 2019
%e A274745 Some solutions for n=4:
%e A274745 ..0..1..2..1. .0..1..2..1. .0..1..0..2. .0..1..2..1. .0..1..0..2
%e A274745 ..2..0..1..0. .2..0..1..2. .1..2..1..0. .1..0..1..0. .1..0..2..0
%e A274745 ..1..2..0..1. .0..1..0..1. .2..1..2..1. .0..1..2..1. .0..2..0..2
%e A274745 ..0..1..2..0. .2..0..2..0. .1..2..1..0. .2..0..1..2. .2..0..2..1
%Y A274745 Column 4 of A274749.
%K A274745 nonn
%O A274745 1,1
%A A274745 _R. H. Hardin_, Jul 04 2016