%I #4 Aug 09 2018 09:43:11

%S 1,3,6,10,21,46,102,220,491,1077,2393,5271,11682,25799,57090,126209,

%T 279123,617274,1364930,3018713,6675002,14762294,32643544,72191407,

%U 159639957,353036505,780698639,1726457594,3817890631,8442936930

%N Number of nX2 0..1 arrays with every element unequal to 1, 2 or 4 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero.

%C Column 2 of A317863.

%H R. H. Hardin, <a href="/A317857/b317857.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = a(n-1) +4*a(n-2) -2*a(n-3) -2*a(n-4) +a(n-5) -4*a(n-6) +4*a(n-7) -a(n-8)

%e Some solutions for n=5

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

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

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

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

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

%Y Cf. A317863.

%K nonn

%O 1,2

%A _R. H. Hardin_, Aug 09 2018