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%I #8 Mar 02 2018 14:14:00
%S 2,15,178,2614,40148,622645,9676364,150442627,2339207390,36372631268,
%T 565564863676,8794081340271,136740955582530,2126212947243743,
%U 33060918081784912,514070948321926226,7993393871925768124
%N Number of n X 2 0..3 arrays with values 0..3 introduced in row major order and each element equal to no more than two horizontal and vertical neighbors.
%C Column 2 of A200801.
%H R. H. Hardin, <a href="/A200795/b200795.txt">Table of n, a(n) for n = 1..200</a>
%F Empirical: a(n) = 18*a(n-1) - 35*a(n-2) - 48*a(n-3) - 11*a(n-4) + 90*a(n-5) + 36*a(n-6) - 12*a(n-7) - 36*a(n-8) for n>10.
%F Empirical g.f.: x*(1 - x)*(2 - 19*x - 41*x^2 - 10*x^3 + 58*x^4 + 58*x^5 - 28*x^7 - 12*x^8) / ((1 - 3*x - x^2 + 2*x^4)*(1 - 15*x - 9*x^2 + 6*x^3 + 18*x^4)). - _Colin Barker_, Mar 02 2018
%e Some solutions for n=3:
%e ..0..1....0..1....0..0....0..1....0..1....0..1....0..1....0..1....0..1....0..1
%e ..2..1....1..2....1..0....1..1....2..3....1..1....2..0....2..1....2..0....2..3
%e ..3..2....3..2....0..0....1..0....1..1....1..2....3..3....3..1....0..0....1..0
%Y Cf. A200801.
%K nonn
%O 1,1
%A _R. H. Hardin_, Nov 22 2011
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