A229374 - OEIS

%I #9 Sep 14 2018 15:59:06

%S 8,30,126,518,2138,8818,36374,150038,618890,2552850,10530214,43435926,

%T 179168218,739048370,3048489846,12574671318,51869078378,213954005138,

%U 882535756294,3640358873558,15016063240250,61939540321970

%N Number of n X 2 0..2 arrays avoiding 11 horizontally, 22 vertically and 00 diagonally or antidiagonally.

%H R. H. Hardin, <a href="/A229374/b229374.txt">Table of n, a(n) for n = 1..210</a>

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

%F Empirical g.f.: 2*x*(4 - x - x^2) / (1 - 4*x - x^2 + 2*x^3). - _Colin Barker_, Sep 14 2018

%e Some solutions for n=4:

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

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

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

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

%Y Column 2 of A229380.

%K nonn

%O 1,1

%A _R. H. Hardin_, Sep 21 2013