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%I #9 May 11 2018 09:53:57
%S 1,4,10,18,28,47,93,189,357,640,1156,2162,4102,7697,14243,26307,48917,
%T 91394,170572,317326,589634,1096821,2042877,3805343,7083795,13181280,
%U 24530278,45664276,85014554,158256855,294565501,548276423,1020572419
%N Number of n X 4 0..4 arrays with each element equal to the number its horizontal and vertical neighbors equal to 2.
%C Every 0 is next to 0 2's, every 1 is next to 1 2's, every 2 is next to 2 2's, every 3 is next to 3 2's, every 4 is next to 4 2's.
%C Column 4 of A197061.
%H R. H. Hardin, <a href="/A197057/b197057.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = a(n-1) +a(n-3) +2*a(n-4) +3*a(n-5) +2*a(n-6) -a(n-7) -3*a(n-8) -2*a(n-9).
%F Empirical g.f.: x*(1 + x)*(1 + x + x^2)*(1 + x + 2*x^2 - x^4 - 2*x^5) / (1 - x - x^3 - 2*x^4 - 3*x^5 - 2*x^6 + x^7 + 3*x^8 + 2*x^9). - _Colin Barker_, May 11 2018
%e Some solutions for n=5:
%e ..0..0..0..0....0..0..0..0....0..0..0..0....0..0..0..0....0..0..0..0
%e ..0..1..1..1....0..0..0..0....1..1..1..0....1..1..1..1....1..1..0..0
%e ..1..2..2..2....0..0..0..0....2..2..2..1....2..2..2..2....2..2..1..0
%e ..1..2..4..2....0..0..0..0....2..4..2..1....2..3..3..2....2..2..1..0
%e ..1..2..2..2....0..0..0..0....2..2..2..1....2..2..2..2....1..1..0..0
%Y Cf. A197061.
%K nonn
%O 1,2
%A _R. H. Hardin_, Oct 09 2011
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