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%I #8 Jun 04 2018 05:47:39
%S 3,20,102,565,3042,16538,89610,486103,2635899,14295131,77522409,
%T 420410296,2279906481,12364072580,67051079697,363621959233,
%U 1971943176024,10693963589630,57993991716273,314504819239756,1705578083028348
%N Number of n X 3 binary arrays with every 1 immediately preceded by 0 to the left or above.
%C Column 3 of A203362.
%H R. H. Hardin, <a href="/A203357/b203357.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 3*a(n-1) +12*a(n-2) +6*a(n-3) +a(n-4).
%F Empirical g.f.: x*(3 + 11*x + 6*x^2 + x^3) / (1 - 3*x - 12*x^2 - 6*x^3 - x^4). - _Colin Barker_, Jun 04 2018
%e Some solutions for n=5:
%e ..0..1..0....0..1..0....0..0..0....0..0..0....0..0..1....0..0..1....0..1..0
%e ..0..0..0....0..0..0....0..0..1....0..1..1....1..0..1....1..0..0....0..1..0
%e ..0..0..1....0..0..1....1..1..0....0..1..0....0..0..0....0..1..0....0..0..1
%e ..0..0..0....0..0..1....0..1..0....1..0..1....1..0..0....0..1..0....0..1..0
%e ..0..1..0....0..1..0....0..1..0....0..0..0....0..0..0....0..1..0....0..1..1
%Y Cf. A203362.
%K nonn
%O 1,1
%A _R. H. Hardin_, Dec 31 2011
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