A276293 - OEIS

%I #8 Feb 05 2019 07:53:34

%S 1,4,11,31,88,250,710,2016,5724,16252,46144,131016,371992,1056192,

%T 2998832,8514544,24175232,68640416,194889824,553348096,1571113920,

%U 4460842944,12665612288,35961305216,102104457600,289903834112

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

%H R. H. Hardin, <a href="/A276293/b276293.txt">Table of n, a(n) for n = 1..210</a>

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

%F Empirical g.f.: x*(1 - x^2 + x^3) / (1 - 4*x + 4*x^2 - 2*x^3). - _Colin Barker_, Feb 05 2019

%e Some solutions for n=4:

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

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

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

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

%Y Column 2 of A276299.

%K nonn

%O 1,2

%A _R. H. Hardin_, Aug 28 2016