A232922 - OEIS

%I #8 Oct 06 2018 05:47:59

%S 27,54,246,912,3612,13992,54600,212544,828048,3225120,12562464,

%T 48931776,190594944,742387008,2891677248,11263389888,43872104640,

%U 170886518976,665621195712,2592665453760,10098708106176,39335543742144

%N Number of 3 X n 0..2 arrays with no element x(i,j) adjacent to value 2-x(i,j) horizontally, diagonally or antidiagonally.

%H R. H. Hardin, <a href="/A232922/b232922.txt">Table of n, a(n) for n = 1..210</a>

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

%F Empirical g.f.: 3*x*(9 - 9*x - 8*x^2 + 4*x^3) / (1 - 3*x - 4*x^2 + 2*x^3). - _Colin Barker_, Oct 06 2018

%e Some solutions for n=5:

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

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

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

%Y Row 3 of A232920.

%K nonn

%O 1,1

%A _R. H. Hardin_, Dec 02 2013