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%I #4 Mar 25 2018 11:25:26
%S 3,4,6,9,15,26,46,83,151,276,506,929,1707,3138,5770,10611,19515,35892,
%T 66014,121417,223319,410746,755478,1389539,2555759,4700772,8646066,
%U 15902593,29249427,53798082,98950098,181997603,334745779,615693476
%N Number of nX3 0..1 arrays with every element equal to 0, 1 or 4 horizontally or vertically adjacent elements, with upper left element zero.
%C Column 3 of A301662.
%H R. H. Hardin, <a href="/A301657/b301657.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 2*a(n-1) -a(n-4)
%e Some solutions for n=5
%e ..0..0..1. .0..1..0. .0..1..0. .0..1..0. .0..1..0. .0..1..0. .0..1..1
%e ..1..1..0. .1..1..1. .0..1..0. .1..0..1. .1..1..1. .1..0..1. .1..0..0
%e ..0..0..1. .0..1..0. .1..0..1. .1..0..1. .0..1..0. .0..0..0. .0..1..1
%e ..1..1..0. .1..0..1. .1..0..1. .0..1..0. .1..0..1. .1..0..1. .1..0..0
%e ..0..0..1. .0..1..0. .0..1..0. .0..1..0. .1..0..1. .0..1..0. .0..1..1
%Y Cf. A301662.
%K nonn
%O 1,1
%A _R. H. Hardin_, Mar 25 2018