A275184 - OEIS

%I #8 Feb 01 2019 05:32:27

%S 4,12,41,141,482,1651,5653,19356,66277,226937,777050,2660679,9110369,

%T 31194604,106812721,365734965,1252304626,4287987275,14682397949,

%U 50273658876,172140871373,589423572097,2018231606314,6910580115135

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

%H R. H. Hardin, <a href="/A275184/b275184.txt">Table of n, a(n) for n = 1..210</a>

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

%F Empirical g.f.: x*(4 + 4*x + x^2 - x^3) / (1 - 2*x - 4*x^2 - 3*x^3). - _Colin Barker_, Feb 01 2019

%e Some solutions for n=4:

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

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

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

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

%Y Row 4 of A275183.

%K nonn

%O 1,1

%A _R. H. Hardin_, Jul 19 2016