A207719 - OEIS

%I #8 Jun 25 2018 12:21:00

%S 9,81,387,2205,12015,66339,364869,2009223,11059965,60888177,335192787,

%T 1845279405,10158455727,55923440859,307864679445,1694829122631,

%U 9330221332989,51363898889337,282763934436339,1556646681947805

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

%C Row 4 of A207717.

%H R. H. Hardin, <a href="/A207719/b207719.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 4*a(n-1) +10*a(n-2) -8*a(n-3) -9*a(n-4) +6*a(n-5).

%F Empirical g.f.: 9*x*(1 - x)*(1 + 6*x + 3*x^2 - 6*x^3) / (1 - 4*x - 10*x^2 + 8*x^3 + 9*x^4 - 6*x^5). - _Colin Barker_, Jun 25 2018

%e Some solutions for n=4:

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

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

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

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

%Y Cf. A207717.

%K nonn

%O 1,1

%A _R. H. Hardin_, Feb 19 2012