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A269007
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Number of n X 4 binary arrays with some element plus some horizontally, diagonally or antidiagonally adjacent neighbor totalling two exactly once.
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1
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5, 36, 305, 2136, 14240, 91048, 566656, 3456320, 20760192, 123186784, 723791744, 4218132480, 24414483712, 140486492800, 804321836032, 4584741088256, 26032741150720, 147311358346752, 831044097026048, 4675403505475584
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OFFSET
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1,1
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LINKS
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FORMULA
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Empirical: a(n) = 12*a(n-1) - 40*a(n-2) + 8*a(n-3) + 92*a(n-4) - 32*a(n-5) - 64*a(n-6) for n>7.
Empirical g.f.: x*(5 - 24*x + 73*x^2 - 124*x^3 + 60*x^4 + 16*x^5 + 4*x^6) / (1 - 6*x + 2*x^2 + 8*x^3)^2. - Colin Barker, Jan 18 2019
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EXAMPLE
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Some solutions for n=4:
..0..0..1..0. .1..0..1..0. .0..0..1..0. .0..1..0..0. .0..0..0..0
..0..0..0..1. .1..0..0..0. .0..1..0..0. .0..1..0..1. .0..1..0..0
..0..0..0..1. .0..1..0..1. .0..0..0..0. .1..0..0..0. .0..0..1..0
..0..1..0..1. .0..0..0..0. .1..0..0..1. .0..0..0..1. .1..0..1..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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