%I #7 Sep 20 2018 09:19:27
%S 3,122,1109,10227,89331,747299,6049298,47723226,368769958,2801445986,
%T 20980532622,155235487082,1136689596246,8248224017298,59378458285438,
%U 424468785559258,3015393888558342,21301249097825858,149716107860461294
%N Number of defective 3-colorings of an n X 4 0..2 array connected horizontally, diagonally and antidiagonally with exactly two mistakes, and colors introduced in row-major 0..2 order.
%H R. H. Hardin, <a href="/A229633/b229633.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 21*a(n-1) - 159*a(n-2) + 511*a(n-3) - 636*a(n-4) + 336*a(n-5) - 64*a(n-6) for n>9.
%F Empirical g.f.: x*(3 + 59*x - 976*x^2 + 4803*x^3 - 9539*x^4 + 7326*x^5 - 1825*x^6 - 76*x^7 + 25*x^8) / (1 - 7*x + 4*x^2)^3. - _Colin Barker_, Sep 20 2018
%e Some solutions for n=3:
%e ..0..1..2..0....0..1..0..1....0..1..2..0....0..1..1..0....0..0..1..2
%e ..0..1..2..0....2..1..0..2....2..0..2..0....0..1..2..0....2..0..1..2
%e ..2..1..1..0....0..1..2..2....1..0..1..1....0..1..2..1....2..0..1..2
%Y Column 4 of A229637.
%K nonn
%O 1,1
%A _R. H. Hardin_, Sep 27 2013