%I #4 Aug 12 2018 19:33:17
%S 2,8,28,97,338,1178,4105,14305,49850,173717,605368,2109583,7351463,
%T 25618337,89274637,311103754,1084132616,3777979256,13165480909,
%U 45878993986,159878860766,557144956745,1941535618525,6765852427390
%N Number of nX2 0..1 arrays with every element unequal to 0, 1, 2 or 3 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero.
%C Column 2 of A318016.
%H R. H. Hardin, <a href="/A318010/b318010.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 4*a(n-1) -2*a(n-2) +a(n-3) -a(n-4)
%e Some solutions for n=5
%e ..0..0. .0..1. .0..1. .0..1. .0..1. .0..0. .0..1. .0..0. .0..0. .0..1
%e ..1..0. .0..0. .0..1. .0..0. .1..1. .1..0. .0..1. .1..1. .0..0. .0..0
%e ..1..0. .1..0. .1..0. .0..1. .1..0. .1..0. .1..1. .0..1. .1..1. .1..1
%e ..1..1. .1..1. .0..0. .1..1. .1..0. .1..1. .1..0. .0..1. .0..1. .1..0
%e ..0..0. .1..0. .0..0. .0..1. .1..1. .1..1. .1..0. .1..1. .0..0. .1..0
%Y Cf. A318016.
%K nonn
%O 1,1
%A _R. H. Hardin_, Aug 12 2018