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 A229679 Number of defective 3-colorings of an n X 2 0..2 array connected diagonally and antidiagonally with exactly two mistakes, and colors introduced in row-major 0..2 order. 1

%I

%S 0,2,36,360,2688,17280,101376,559104,2949120,15040512,74711040,

%T 363331584,1736441856,8178892800,38050725888,175154135040,

%U 798863917056,3614214979584,16234976378880,72464688218112,321607151124480

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

%C Column 2 of A229685.

%H R. H. Hardin, <a href="/A229679/b229679.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 12*a(n-1) -48*a(n-2) +64*a(n-3) for n>5.

%F Empirical: g.f. 2*x^2 -12*x^3*(3-6*x+8*x^2) ) / (4*x-1)^3. - _R. J. Mathar_, Sep 29 2013

%F Empirical: a(n) = 3*2^(2*n-5)*(3 - 5*n + 2*n^2) for n>2. - _Colin Barker_, Jun 13 2017

%e Some solutions for n=3

%e ..0..1....0..1....0..1....0..0....0..1....0..0....0..1....0..1....0..1....0..1

%e ..1..1....1..2....1..0....1..0....1..1....0..1....2..0....1..2....2..2....1..1

%e ..1..2....2..2....2..2....1..1....0..1....2..0....2..2....0..1....2..2....2..1

%K nonn

%O 1,2

%A _R. H. Hardin_, Sep 27 2013

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Last modified August 12 23:19 EDT 2020. Contains 336440 sequences. (Running on oeis4.)