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A232077
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Number of (1+1) X (n+1) 0..1 arrays with every element equal to some horizontal, diagonal or antidiagonal neighbor, with top left element zero.
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5
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3, 15, 46, 161, 601, 2208, 8053, 29415, 107534, 393061, 1436589, 5250624, 19190841, 70141747, 256364934, 937002409, 3424702513, 12517136672, 45749581901, 167212702063, 611155044830, 2233744710845, 8164238313221, 29839930638080
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OFFSET
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1,1
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COMMENTS
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LINKS
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FORMULA
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Empirical: a(n) = 3*a(n-1) + a(n-2) + 4*a(n-3) + 4*a(n-4).
Empirical g.f.: x*(1 + 2*x)*(3 - 2*x^2) / (1 - 3*x - x^2 - 4*x^3 - 4*x^4). - Colin Barker, Mar 19 2018
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EXAMPLE
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Some solutions for n=7:
..0..1..0..1..0..1..0..0....0..0..1..0..0..0..0..1....0..1..0..0..1..1..1..1
..1..0..1..0..1..1..0..0....0..1..0..1..1..1..1..0....1..0..0..0..1..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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