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A253029
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Number of (n+2) X (1+2) 0..2 arrays with every consecutive three elements in every row and column having exactly two distinct values, and new values 0 upwards introduced in row major order.
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1
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297, 1647, 9126, 50571, 280233, 1552878, 8605089, 47684079, 264235662, 1464230547, 8113859721, 44961990246, 249151530393, 1380643622703, 7650672704694, 42395294391579, 234928490071977, 1301828333534622
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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) = 5*a(n-1) + 3*a(n-2).
G.f.: 27*x*(11 + 6*x) / (1 - 5*x - 3*x^2).
a(n) = (27*2^(-n)*((5-sqrt(37))^n*(-6+sqrt(37)) + (5+sqrt(37))^n*(6+sqrt(37)))) / sqrt(37).
(End)
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EXAMPLE
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Some solutions for n=4:
..0..1..0....0..1..0....0..0..1....0..0..1....0..1..1....0..0..1....0..0..1
..0..2..0....1..0..0....1..0..0....1..1..2....2..1..1....2..1..2....1..2..2
..2..1..2....0..0..1....0..1..1....0..0..2....0..0..2....0..0..1....0..0..1
..0..2..2....0..1..0....0..1..0....1..1..0....0..0..2....0..0..2....1..2..1
..0..1..1....1..0..1....1..0..1....0..0..2....2..2..1....2..1..1....0..2..0
..2..1..2....1..0..0....0..1..1....0..0..2....2..0..2....2..0..2....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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