%I #4 Aug 15 2018 13:09:04
%S 1,5,18,67,249,925,3437,12770,47447,176289,655001,2433653,9042226,
%T 33596347,124827065,463794357,1723225693,6402636738,23788965871,
%U 88387787777,328404398513,1220184956261,4533591310674,16844536614515
%N Number of nX2 0..1 arrays with every element unequal to 1, 2, 3 or 4 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero.
%C Column 2 of A318068.
%H R. H. Hardin, <a href="/A318062/b318062.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 3*a(n-1) +3*a(n-2) -a(n-3) -a(n-4)
%e Some solutions for n=5
%e ..0..1. .0..0. .0..1. .0..0. .0..0. .0..0. .0..0. .0..1. .0..1. .0..1
%e ..1..1. .1..0. .0..0. .1..1. .1..1. .1..0. .1..0. .1..0. .0..0. .0..1
%e ..0..1. .0..0. .1..0. .0..1. .1..0. .1..1. .0..1. .0..1. .1..0. .0..0
%e ..0..0. .0..1. .0..0. .1..1. .1..0. .0..0. .1..1. .0..1. .1..1. .1..1
%e ..1..1. .0..0. .1..1. .0..1. .1..0. .1..1. .0..1. .1..0. .0..0. .1..0
%Y Cf. A318068.
%K nonn
%O 1,2
%A _R. H. Hardin_, Aug 15 2018