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A277939 Number of n X 2 0..2 arrays with every element plus 1 mod 3 equal to some element at offset (-1,0) (-1,1) (0,-1) (0,1) or (1,0), with upper left element zero. 1

%I #9 Feb 06 2019 06:05:40

%S 0,3,14,74,377,1932,9888,50619,259118,1326434,6790049,34758444,

%T 177929400,910825347,4662539246,23867662778,122179202441,625438596492,

%U 3201636859344,16389264488331,83897082108014,429471401309714

%N Number of n X 2 0..2 arrays with every element plus 1 mod 3 equal to some element at offset (-1,0) (-1,1) (0,-1) (0,1) or (1,0), with upper left element zero.

%H R. H. Hardin, <a href="/A277939/b277939.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 4*a(n-1) + 6*a(n-2) - a(n-3) - 2*a(n-4).

%F Empirical g.f.: x^2*(3 + 2*x) / ((1 + x)*(1 - 5*x - x^2 + 2*x^3)). - _Colin Barker_, Feb 06 2019

%e Some solutions for n=4:

%e ..0..1. .0..2. .0..1. .0..2. .0..2. .0..2. .0..1. .0..2. .0..2. .0..2

%e ..2..2. .1..1. .1..2. .1..2. .1..0. .1..1. .0..2. .1..0. .1..1. .1..0

%e ..1..0. .1..0. .1..0. .0..0. .0..1. .2..1. .0..1. .1..2. .2..1. .0..2

%e ..0..2. .2..1. .1..2. .2..1. .0..2. .0..0. .0..0. .0..1. .0..2. .1..1

%Y Column 2 of A277945.

%K nonn

%O 1,2

%A _R. H. Hardin_, Nov 05 2016

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Last modified March 28 16:12 EDT 2024. Contains 371254 sequences. (Running on oeis4.)