A229667 - OEIS

%I #6 Sep 28 2013 18:53:54

%S 1,61,1555,19805,194575,1673561,13271403,99602405,718231671,

%T 5024073665,34312328499,229845418733,1515221386655,9855527727977,

%U 63373619492795,403501000362805,2547056875288967,15956625712036945,99294517974997251

%N Number of defective 4-colorings of an nX3 0..3 array connected horizontally, antidiagonally and vertically with exactly two mistakes, and colors introduced in row-major 0..3 order

%C Column 3 of A229672

%H R. H. Hardin, <a href="/A229667/b229667.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 21*a(n-1) -171*a(n-2) +679*a(n-3) -1368*a(n-4) +1344*a(n-5) -512*a(n-6) for n>7.

%F Empirical: G.f. x -x^2*(-61-274*x+2419*x^2-3156*x^3-1744*x^4+3392*x^5) / (8*x^2-7*x+1)^3. - _R. J. Mathar_, Sep 29 2013

%e Some solutions for n=3

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

%e ..2..3..2....2..3..2....2..3..2....0..2..1....3..1..1....1..2..2....0..0..3

%e ..3..2..0....1..1..0....2..0..2....1..3..1....0..2..3....3..0..3....2..1..2

%K nonn

%O 1,2

%A _R. H. Hardin_, Sep 27 2013