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%I #8 Sep 21 2018 08:14:17
%S 3,422,2347,6561,15075,32548,69198,147376,315786,680124,1468934,
%T 3174760,6855906,14780020,31793694,68231136,146079674,312025516,
%U 665011638,1414360024,3002176530,6360776292,13453355726,28408158544,59894811114
%N Number of defective 4-colorings of an n X 4 0..3 array connected horizontally, vertically, diagonally and antidiagonally with exactly two mistakes, and colors introduced in row-major 0..3 order.
%H R. H. Hardin, <a href="/A229751/b229751.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 9*a(n-1) - 33*a(n-2) + 63*a(n-3) - 66*a(n-4) + 36*a(n-5) - 8*a(n-6) for n>11.
%F Empirical g.f.: x*(3 + 395*x - 1352*x^2 - 825*x^3 + 7089*x^4 - 6731*x^5 + 132*x^6 + 863*x^7 - 58*x^8 - 60*x^9 + 8*x^10) / ((1 - x)^3*(1 - 2*x)^3). - _Colin Barker_, Sep 21 2018
%e Some solutions for n=4:
%e ..0..1..0..2....0..1..0..2....0..1..2..1....0..1..0..0....0..1..2..0
%e ..2..3..0..3....2..3..2..1....2..0..3..0....2..1..2..3....2..3..1..3
%e ..1..1..2..1....0..1..0..3....3..1..2..1....0..3..0..1....0..0..2..0
%e ..3..0..3..0....2..1..2..1....2..0..2..0....2..1..2..3....3..1..3..1
%Y Column 4 of A229755.
%K nonn
%O 1,1
%A _R. H. Hardin_, Sep 28 2013
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