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Equals two maps: number of nX2 binary arrays indicating the locations of corresponding elements equal to exactly two of their king-move neighbors in a random 0..1 nX2 array
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%I #5 Dec 08 2012 14:19:05

%S 1,5,18,37,85,184,393,826,1726,3568,7342,15009,30562,62034,125493,

%T 253311,510438,1026775,2063029,4141268,8305979,16649028,33356608,

%U 66803160,133746856,267712961,535761706,1072043156,2144889675,4291005857

%N Equals two maps: number of nX2 binary arrays indicating the locations of corresponding elements equal to exactly two of their king-move neighbors in a random 0..1 nX2 array

%C Column 2 of A220247

%H R. H. Hardin, <a href="/A220243/b220243.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 3*a(n-1) -a(n-2) +3*a(n-3) -14*a(n-4) +2*a(n-5) +3*a(n-6) +21*a(n-7) +6*a(n-8) -16*a(n-9) -12*a(n-10) -16*a(n-11) +12*a(n-12) +4*a(n-13) +8*a(n-14) for n>16

%e Some solutions for n=3

%e ..0..1....1..1....1..1....0..1....1..0....1..1....1..0....1..0....0..0....0..1

%e ..1..1....1..1....0..0....0..0....0..0....0..0....0..0....1..1....0..0....0..0

%e ..0..0....1..1....0..0....0..0....0..1....1..1....0..0....0..0....1..0....0..1

%K nonn

%O 1,2

%A _R. H. Hardin_ Dec 08 2012