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A208253
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Number of n X 3 0..2 arrays with new values 0..2 introduced in row major order and no element equal to more than one of its immediate leftward or upward neighbors.
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1
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5, 96, 2040, 43344, 920928, 19566912, 415737216, 8833148160, 187677464064, 3987573838848, 84723785029632, 1800122089230336, 38247105402593280, 812634365429366784, 17266002353004576768, 366849901919230820352
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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) = 22*a(n-1) - 16*a(n-2) for n>3.
G.f.: x*(1 - 2*x)*(5 - 4*x) / (1 - 22*x + 16*x^2).
a(n) = (1/32)*sqrt(3/35)*((11-sqrt(105))^n*(-13+sqrt(105)) + (11+sqrt(105))^n*(13+sqrt(105))) for n>1.
(End)
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EXAMPLE
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Some solutions for n=4:
..0..0..1....0..0..0....0..1..0....0..0..1....0..0..0....0..1..2....0..0..1
..2..0..0....0..1..2....0..1..1....2..0..2....1..2..1....1..2..0....1..1..2
..2..0..1....2..0..0....1..0..2....0..2..0....0..2..2....0..1..0....1..0..1
..2..2..2....1..0..1....1..2..0....2..0..2....0..0..2....2..0..1....2..1..2
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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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