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%I #9 May 11 2018 09:56:42
%S 1,7,18,55,163,484,1439,4275,12704,37749,112171,333314,990437,2943067,
%T 8745274,25986435,77218255,229452748,681814987,2026001783,6020230272,
%U 17889013145,53156902119,157954841890,469360159865,1394695832255
%N Number of n X 2 0..4 arrays with each element x equal to the number its horizontal and vertical neighbors equal to 4,4,0,0,1 for x=0,1,2,3,4.
%C Every 0 is next to 0 4's, every 1 is next to 1 4's, every 2 is next to 2 0's, every 3 is next to 3 0's, every 4 is next to 4 1's.
%C Column 2 of A197098.
%H R. H. Hardin, <a href="/A197092/b197092.txt">Table of n, a(n) for n = 1..200</a>
%F Empirical: a(n) = 2*a(n-1) +3*a(n-2) -a(n-4).
%F Empirical g.f.: x*(1 + 5*x + x^2 - 2*x^3) / (1 - 2*x - 3*x^2 + x^4). - _Colin Barker_, May 11 2018
%e Some solutions for n=4:
%e ..0..0....0..0....2..0....0..2....2..0....2..0....2..0....0..2....2..0....0..2
%e ..0..3....3..0....0..2....0..0....0..3....0..3....0..3....2..0....0..3....2..0
%e ..3..0....0..3....0..2....3..0....0..0....0..0....0..0....2..0....3..0....2..0
%e ..0..2....2..0....0..0....0..2....2..0....0..2....0..0....0..0....0..2....0..2
%Y Cf. A197098.
%K nonn
%O 1,2
%A _R. H. Hardin_, Oct 10 2011
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