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A281949
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Number of nX2 0..1 arrays with no element unequal to more than four of its king-move neighbors and with new values introduced in order 0 sequentially upwards.
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8
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2, 8, 30, 112, 420, 1576, 5912, 22176, 83184, 312032, 1170464, 4390528, 16469312, 61778048, 231735680, 869263872, 3260696320, 12231200256, 45880463872, 172102240256, 645572834304, 2421608712192, 9083698141184, 34073866477568
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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) = 4*a(n-1) -2*a(n-2) +4*a(n-3)
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EXAMPLE
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Some solutions for n=4
..0..1. .0..0. .0..1. .0..0. .0..0. .0..1. .0..1. .0..0. .0..1. .0..0
..0..1. .0..0. .1..1. .1..0. .1..0. .0..1. .1..1. .0..1. .0..0. .0..1
..0..1. .0..0. .0..1. .1..1. .1..1. .1..1. .0..1. .0..1. .0..0. .1..0
..1..1. .1..1. .1..0. .1..1. .0..0. .0..0. .0..1. .0..0. .1..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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