A208035 - OEIS

%I #11 Jun 27 2018 05:50:34

%S 9,81,289,961,3249,11025,37249,126025,426409,1442401,4879681,16507969,

%T 55845729,188925025,639128961,2162157001,7314525625,24744863025,

%U 83711270241,283193201281,958035736849,3241011678961,10964263980289

%N Number of n X 4 0..1 arrays avoiding 0 0 0 and 0 1 0 horizontally and 0 0 0 and 1 0 1 vertically.

%C Column 4 of A208039.

%H R. H. Hardin, <a href="/A208035/b208035.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 2*a(n-1) + 3*a(n-2) + 6*a(n-3) - a(n-4) - a(n-6) for n>7.

%F Empirical g.f.: x*(9 + 63*x + 100*x^2 + 86*x^3 - 17*x^4 - 9*x^5 - 16*x^6) / ((1 + x + x^2 - x^3)*(1 - 3*x - x^2 - x^3)). - _Colin Barker_, Jun 27 2018

%e Some solutions for n=4:

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

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

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

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

%Y Cf. A208039.

%K nonn

%O 1,1

%A _R. H. Hardin_, Feb 22 2012