%I #9 Jul 15 2018 06:53:26

%S 0,29,400,4298,42520,406580,3828928,35804264,333688864,3104980304,

%T 28869996928,268334928032,2493631919488,23171354998592,

%U 215304570112000,2000537970249344,18588159494998528,172712625468359936

%N Number of (n+1) X 2 0..3 arrays containing all values 0..3 with every 2 X 2 subblock having three distinct values, and new values 0..3 introduced in row major order.

%C Column 1 of A210267.

%H R. H. Hardin, <a href="/A210260/b210260.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 12*a(n-1) - 18*a(n-2) - 64*a(n-3) - 24*a(n-4).

%F Empirical g.f.: x^2*(29 + 52*x + 20*x^2) / ((1 - 4*x - 2*x^2)*(1 - 8*x - 12*x^2)). - _Colin Barker_, Jul 15 2018

%e Some solutions for n=4:

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

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

%e ..3..1....0..1....1..3....1..1....0..2....1..3....1..0....3..1....1..1....3..2

%e ..0..1....1..2....1..2....2..3....3..3....2..1....1..2....1..2....3..0....0..2

%e ..3..3....3..3....3..2....2..0....0..1....2..3....2..3....0..1....1..0....0..3

%Y Cf. A210267.

%K nonn

%O 1,2

%A _R. H. Hardin_, Mar 19 2012