%I #4 Apr 02 2018 14:50:47
%S 4,6,7,12,20,34,56,94,156,262,436,730,1216,2034,3392,5670,9460,15806,
%T 26380,44066,73560,122858,205112,342542,571916,955062,1594660,2662890,
%U 4446320,7424674,12397424,20701558,34566948,57720430,96380668,160937266
%N Number of 3Xn 0..1 arrays with every element equal to 0, 1 or 3 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero.
%C Row 3 of A302163.
%H R. H. Hardin, <a href="/A302165/b302165.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = a(n-1) +a(n-2) -a(n-3) +2*a(n-4) for n>6
%e Some solutions for n=5
%e ..0..0..1..0..1. .0..0..1..1..0. .0..1..0..1..0. .0..1..0..1..0
%e ..0..1..0..0..1. .0..1..0..1..0. .0..1..0..1..1. .1..1..0..1..1
%e ..0..1..0..1..0. .0..1..0..1..0. .0..1..0..1..0. .0..1..0..1..0
%Y Cf. A302163.
%K nonn
%O 1,1
%A _R. H. Hardin_, Apr 02 2018