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A233212
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Number of n X 3 0..5 arrays with no element x(i,j) adjacent to value 5-x(i,j) horizontally or antidiagonally, top left element zero, and 1 appearing before 2 3 and 4, and 2 appearing before 3 in row major order.
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1
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6, 376, 35446, 3638416, 380283286, 39892988056, 4187991850726, 439722934529296, 46170567719841766, 4847902462062966136, 509029608397682640406, 53448105729259172362576, 5612051035369765495590646
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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) = 127*a(n-1) - 2331*a(n-2) + 2205*a(n-3).
G.f.: 2*x*(3 - 193*x + 840*x^2) / ((1 - x)*(1 - 21*x)*(1 - 105*x)).
a(n) = (105 + 2*3^(2+n)*7^n + 5^(1+n)*21^n) / 168.
(End)
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EXAMPLE
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Some solutions for n=3:
..0..1..5....0..1..0....0..1..5....0..0..1....0..1..2....0..1..2....0..0..1
..5..2..2....2..2..0....1..2..1....1..2..1....5..1..2....2..2..2....2..0..1
..1..2..1....1..2..5....5..5..5....4..2..2....0..0..3....2..4..5....1..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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