cp's OEIS Frontend

A229638 Number of defective 3-colorings of a 2 X n 0..2 array connected horizontally, diagonally and antidiagonally with exactly two mistakes, and colors introduced in row-major 0..2 order.

%I A229638 #7 Sep 20 2018 09:19:19
%S A229638 0,6,40,122,488,1608,5392,17368,55232,172896,535296,1641376,4992896,
%T A229638 15083648,45297408,135323008,402405376,1191699968,3516119040,
%U A229638 10339711488,30313351168,88624646144,258445856768,751910639616,2182836600832
%N A229638 Number of defective 3-colorings of a 2 X n 0..2 array connected horizontally, diagonally and antidiagonally with exactly two mistakes, and colors introduced in row-major 0..2 order.
%H A229638 R. H. Hardin, <a href="/A229638/b229638.txt">Table of n, a(n) for n = 1..210</a>
%F A229638 Empirical: a(n) = 6*a(n-1) - 6*a(n-2) - 16*a(n-3) + 12*a(n-4) + 24*a(n-5) + 8*a(n-6).
%F A229638 Empirical g.f.: 2*x^2*(1 - x)*(3 + 5*x - 36*x^2 + 10*x^3) / (1 - 2*x - 2*x^2)^3. - _Colin Barker_, Sep 20 2018
%e A229638 Some solutions for n=3:
%e A229638 ..0..1..2....0..1..2....0..1..2....0..1..2....0..0..0....0..0..1....0..1..0
%e A229638 ..0..1..1....2..0..0....2..0..1....1..1..2....1..2..1....1..0..1....1..1..2
%Y A229638 Row 2 of A229637.
%K A229638 nonn
%O A229638 1,2
%A A229638 _R. H. Hardin_, Sep 27 2013