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%I #12 Jun 07 2018 06:18:47
%S 0,4,4,16,68,212,776,3076,11540,44944,177748,700292,2779272,11069140,
%T 44107780,176038288,703199588,2809956020,11232774920,44913243940,
%U 179603461748,718287355024,2872823053300,11490415637348,45959392743048
%N Number of n X 2 0..3 arrays with every element neighboring horizontally or vertically both a 0 and a 1, and 2 introduced before 3 in row major order.
%C Column 2 of A204301.
%H R. H. Hardin, <a href="/A204295/b204295.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 4*a(n-1) +2*a(n-2) +4*a(n-3) -42*a(n-4) -30*a(n-5) +13*a(n-6) +38*a(n-7) +28*a(n-8) -16*a(n-9).
%F Empirical g.f.: 4*x^2*(1 - 3*x - 2*x^2 - 5*x^3 + 15*x^4 + 4*x^5 + 4*x^6 - 8*x^7) / ((1 - x)*(1 + x)*(1 - 4*x)*(1 - 3*x + x^2)*(1 + x + x^2)*(1 + 2*x + 4*x^2)). - _Colin Barker_, Jun 07 2018
%e Some solutions for n=5:
%e ..0..0....0..1....0..1....1..1....0..0....1..0....0..1....0..1....1..0....0..0
%e ..1..1....0..1....0..1....0..0....1..1....1..0....0..1....0..1....1..0....1..1
%e ..0..0....2..1....1..1....2..1....0..1....0..1....2..0....0..1....1..0....0..2
%e ..1..1....1..0....0..0....1..1....0..0....0..1....1..0....1..0....1..0....0..1
%e ..0..0....1..0....1..1....0..0....1..1....0..1....1..0....1..0....1..0....0..1
%Y Cf. A204301.
%K nonn
%O 1,2
%A _R. H. Hardin_, Jan 14 2012
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