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A221405
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Number of nX4 arrays of occupancy after each element stays put or moves to some horizontal or vertical neighbor, with every occupancy equal to zero or two
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1
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4, 44, 436, 4518, 47156, 492102, 5133044, 53529806, 558164472, 5819704716, 60677191216, 632619159318, 6595610902832, 68764677891112, 716926331557236, 7474513869766556, 77927543824707370, 812454058048811426
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OFFSET
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1,1
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COMMENTS
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LINKS
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FORMULA
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Empirical: a(n) = 19*a(n-1) -110*a(n-2) +250*a(n-3) -446*a(n-4) +939*a(n-5) -1112*a(n-6) -343*a(n-7) -822*a(n-8) +692*a(n-9) +1957*a(n-10) +2810*a(n-11) -1975*a(n-12) -59*a(n-13) -2679*a(n-14) +738*a(n-15) +1088*a(n-16) +1258*a(n-17) -418*a(n-18) -562*a(n-19) +192*a(n-20) +336*a(n-21) +32*a(n-22) -32*a(n-23)
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EXAMPLE
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Some solutions for n=3
..0..2..2..0....0..2..0..2....2..2..0..2....2..2..0..2....0..2..0..0
..2..2..0..0....0..2..0..2....0..0..0..2....0..2..0..0....2..0..0..2
..0..0..2..2....2..0..0..2....2..2..0..0....2..0..2..0....2..2..2..0
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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