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A283409
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Number of n X 2 0..1 arrays with no 1 equal to more than three of its horizontal, vertical and antidiagonal neighbors.
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1
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4, 16, 61, 236, 912, 3525, 13624, 52656, 203513, 786568, 3040048, 11749641, 45411804, 175514464, 678355061, 2621810068, 10133171296, 39164225421, 151367869744, 585029621920, 2261111681777, 8739089177552, 33776164295072
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OFFSET
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1,1
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LINKS
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R. H. Hardin, Table of n, a(n) for n = 1..210
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FORMULA
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Empirical: a(n) = 3*a(n-1) + 3*a(n-2) + a(n-3) + a(n-4) + a(n-5).
Empirical g.f.: x*(4 + 4*x + x^2 + x^3 + x^4) / (1 - 3*x - 3*x^2 - x^3 - x^4 - x^5). - Colin Barker, Feb 21 2019
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EXAMPLE
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Some solutions for n=4:
..1..1. .1..0. .1..1. .0..1. .1..1. .1..0. .0..1. .0..1. .1..0. .0..0
..0..0. .0..0. .0..1. .0..0. .1..1. .1..0. .0..0. .1..0. .1..0. .0..1
..0..0. .1..0. .0..1. .0..0. .0..0. .0..1. .0..1. .1..1. .1..1. .1..1
..1..0. .1..0. .1..0. .1..0. .1..1. .0..0. .0..1. .0..1. .1..1. .0..1
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CROSSREFS
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Column 2 of A283415.
Sequence in context: A206570 A206790 A283858 * A192468 A276042 A084859
Adjacent sequences: A283406 A283407 A283408 * A283410 A283411 A283412
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KEYWORD
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nonn
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AUTHOR
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R. H. Hardin, Mar 07 2017
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STATUS
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approved
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