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A318071
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Number of nX4 0..1 arrays with every element unequal to 0, 1, 2 or 5 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero.
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1
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8, 20, 41, 73, 149, 372, 861, 2016, 4901, 11698, 27986, 67359, 161518, 387556, 930666, 2233451, 5360842, 12868595, 30887501, 74139733, 177960357, 427157604, 1025312853, 2461074852, 5907342192, 14179472548, 34035173339, 81695041734
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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) = 2*a(n-1) +a(n-2) +2*a(n-3) -3*a(n-4) -5*a(n-5) -2*a(n-7) +7*a(n-8) -a(n-9) -2*a(n-10) +8*a(n-11) -3*a(n-12) -a(n-13) -3*a(n-14) -3*a(n-15) +4*a(n-16) +a(n-17) -a(n-18) for n>21
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EXAMPLE
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Some solutions for n=5
..0..0..0..0. .0..1..1..1. .0..1..0..0. .0..1..1..1. .0..0..0..0
..0..0..0..0. .1..1..1..1. .1..1..0..0. .1..1..1..1. .0..0..1..0
..0..0..0..0. .1..1..1..1. .1..1..0..0. .0..0..0..0. .0..1..0..0
..1..1..1..1. .1..1..1..1. .1..1..0..0. .0..0..0..0. .0..0..0..0
..1..1..1..0. .1..1..1..1. .1..1..0..0. .0..0..0..1. .0..0..0..1
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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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