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A268991
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Number of n X 4 binary arrays with some element plus some horizontally or antidiagonally adjacent neighbor totalling two not more than once.
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1
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13, 103, 805, 6009, 43512, 308112, 2144780, 14730784, 100087792, 674045392, 4505925696, 29933341056, 197782652096, 1300744853760, 8519586895104, 55600022810880, 361688403251200, 2346083095244800, 15178387509332992
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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) = 16*a(n-1) - 88*a(n-2) + 200*a(n-3) - 208*a(n-4) + 96*a(n-5) - 16*a(n-6) for n>7.
Empirical g.f.: x*(13 - 105*x + 301*x^2 - 407*x^3 + 312*x^4 - 112*x^5 + 4*x^6) / (1 - 8*x + 12*x^2 - 4*x^3)^2. - Colin Barker, Jan 17 2019
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EXAMPLE
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Some solutions for n=4:
..0..1..0..0. .1..0..0..0. .0..1..0..1. .0..0..0..0. .1..0..0..1
..0..1..0..0. .1..0..1..0. .0..0..0..0. .1..0..1..0. .1..1..0..1
..1..0..0..1. .1..0..1..0. .0..0..0..1. .0..1..0..0. .0..0..0..1
..1..0..0..0. .1..0..0..0. .1..0..0..1. .0..0..0..0. .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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