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A196584
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Number of n X 2 0..4 arrays with each element x equal to the number its horizontal and vertical neighbors equal to 3,2,0,1,4 for x=0,1,2,3,4.
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3
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1, 7, 20, 65, 203, 648, 2057, 6527, 20740, 65833, 209091, 663912, 2108281, 6694767, 21258988, 67507481, 214367707, 680719048, 2161603009, 6864108879, 21796779780, 69215046289, 219790389515, 697938050920, 2216282199881, 7037740324047
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OFFSET
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1,2
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COMMENTS
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Every 0 is next to 0 3's, every 1 is next to 1 2's, every 2 is next to 2 0's, every 3 is next to 3 1's, every 4 is next to 4 4's.
Column 2 of A196590.
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LINKS
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R. H. Hardin, Table of n, a(n) for n = 1..200
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FORMULA
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Empirical: a(n) = a(n-1) +6*a(n-2) +4*a(n-3) -3*a(n-4) -a(n-5) -2*a(n-6) -a(n-7).
Empirical g.f.: x*(1 + 6*x + 7*x^2 - x^3 - 7*x^4 - 3*x^5) / (1 - x - 6*x^2 - 4*x^3 + 3*x^4 + x^5 + 2*x^6 + x^7). - Colin Barker, Feb 22 2018
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EXAMPLE
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Some solutions for n=4:
..0..0....0..0....0..2....0..0....0..1....2..0....2..0....0..0....0..2....0..0
..0..0....2..2....0..0....0..2....0..2....0..1....0..2....0..0....2..0....2..2
..2..2....0..0....0..0....0..1....0..0....0..2....0..1....0..0....1..0....0..0
..0..0....0..0....2..0....2..0....0..2....0..0....0..0....0..0....0..0....2..0
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CROSSREFS
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Cf. A196590.
Sequence in context: A219422 A209546 A222549 * A301777 A299181 A299944
Adjacent sequences: A196581 A196582 A196583 * A196585 A196586 A196587
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KEYWORD
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nonn
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AUTHOR
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R. H. Hardin, Oct 04 2011
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STATUS
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approved
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