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A297310
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Number of n X 4 0..1 arrays with every 1 horizontally or antidiagonally adjacent to 1 or 2 neighboring 1s.
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1
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7, 66, 497, 3808, 29212, 223995, 1717882, 13174266, 101033369, 774822892, 5942100272, 45569854023, 349474289622, 2680111429330, 20553721242845, 157626080234992, 1208831279237072, 9270503076704855, 71095304015354510
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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) = 4*a(n-1) + 26*a(n-2) + 22*a(n-3) - 43*a(n-4) - a(n-5) + 7*a(n-6) - a(n-7) - a(n-8) for n>9.
Empirical g.f.: x*(7 + 38*x + 51*x^2 - 50*x^3 - 93*x^4 + 50*x^5 + 2*x^6 - 10*x^7 + x^8) / ((1 - 7*x - 5*x^2 - x^3)*(1 + 3*x - 6*x^3 + 4*x^4 - x^5)). - Colin Barker, Feb 26 2019
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EXAMPLE
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Some solutions for n=5:
..0..1..1..0. .1..1..0..1. .1..1..1..0. .0..1..1..0. .0..0..1..1
..1..0..0..1. .0..0..1..1. .0..1..0..1. .1..1..0..0. .0..1..0..1
..0..1..1..0. .0..0..1..1. .1..0..1..0. .0..1..0..0. .1..0..1..1
..1..0..0..0. .0..0..0..0. .0..1..0..0. .1..0..1..0. .0..0..0..1
..1..1..1..0. .0..1..1..0. .0..1..1..0. .1..1..0..0. .1..1..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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