%I #9 Jul 15 2018 06:53:42
%S 0,35,995,19186,319485,4963700,74362241,1091691712,15840736305,
%T 228277891400,3276198192905,46903413280504,670487434284753,
%U 9575993410570520,136690481022953081,1950506854209691864
%N Number of (n+1) X 2 0..3 arrays containing all values 0..3 with every 2 X 2 subblock having two or three distinct values, and new values 0..3 introduced in row major order.
%C Column 1 of A210320.
%H R. H. Hardin, <a href="/A210313/b210313.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 24*a(n-1) - 141*a(n-2) - 24*a(n-3) + 718*a(n-4) + 768*a(n-5) + 216*a(n-6).
%F Empirical g.f.: x^2*(35 + 155*x + 241*x^2 + 156*x^3 + 36*x^4) / ((1 - 3*x - 2*x^2)*(1 - 8*x - 6*x^2)*(1 - 13*x - 18*x^2)). - _Colin Barker_, Jul 15 2018
%e Some solutions for n=4:
%e ..0..0....0..1....0..0....0..1....0..0....0..0....0..0....0..0....0..1....0..0
%e ..1..0....2..0....0..1....0..2....0..1....1..0....0..1....0..1....0..0....1..0
%e ..1..0....2..3....2..0....0..3....0..0....0..0....1..1....0..0....0..1....0..0
%e ..0..0....1..1....0..1....3..0....0..2....2..3....1..2....1..2....1..1....0..2
%e ..2..3....1..3....3..0....1..3....3..3....1..1....2..3....1..3....2..3....0..3
%Y Cf. A210320.
%K nonn
%O 1,2
%A _R. H. Hardin_, Mar 20 2012