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A229690 Number of defective 3-colorings of an nX4 0..2 array connected horizontally and antidiagonally with exactly two mistakes, and colors introduced in row-major 0..2 order.

%I A229690 #8 Jul 23 2025 05:46:05
%S A229690 3,245,5077,80757,1125333,14461173,175867605,2054728053,23284024533,
%T A229690 257577229557,2794463987157,29833314755445,314218549864917,
%U A229690 3271569607417077,33725758239805653,344669380723927413
%N A229690 Number of defective 3-colorings of an nX4 0..2 array connected horizontally and antidiagonally with exactly two mistakes, and colors introduced in row-major 0..2 order.
%C A229690 Column 4 of A229694
%H A229690 R. H. Hardin, <a href="/A229690/b229690.txt">Table of n, a(n) for n = 1..210</a>
%F A229690 Empirical: a(n) = 27*a(n-1) -243*a(n-2) +729*a(n-3) for n>4.
%F A229690 Empirical: g.f. 3*x-x^2*(245-1538*x+3213*x^2) / (9*x-1)^3. - _R. J. Mathar_, Sep 29 2013
%e A229690 Some solutions for n=3
%e A229690 ..0..0..1..0....0..1..0..2....0..1..2..0....0..1..2..1....0..1..0..2
%e A229690 ..1..0..1..2....2..1..0..0....0..1..0..2....0..2..0..2....2..1..0..1
%e A229690 ..1..0..0..2....2..0..1..2....0..1..2..1....0..1..1..2....2..0..0..1
%K A229690 nonn
%O A229690 1,1
%A A229690 _R. H. Hardin_, Sep 27 2013