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A219286
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Number of n X 3 arrays of the minimum value of corresponding elements and their horizontal or vertical neighbors in a random, but sorted with lexicographically nondecreasing rows and columns, 0..1 n X 3 array.
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1
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3, 6, 19, 42, 79, 136, 220, 339, 502, 719, 1001, 1360, 1809, 2362, 3034, 3841, 4800, 5929, 7247, 8774, 10531, 12540, 14824, 17407, 20314, 23571, 27205, 31244, 35717, 40654, 46086, 52045, 58564, 65677, 73419, 81826, 90935, 100784, 111412, 122859
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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) = (1/24)*n^4 + (1/4)*n^3 - (1/24)*n^2 + (27/4)*n - 11 for n>2.
G.f.: x*(3 - 9*x + 19*x^2 - 23*x^3 + 14*x^4 - 2*x^5 - x^6) / (1 - x)^5.
a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5) for n>7.
(End)
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EXAMPLE
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Some solutions for n=3:
..0..0..1....0..0..1....0..0..0....0..0..0....0..0..0....0..0..0....0..0..0
..0..0..1....0..0..1....0..0..0....0..0..0....0..0..1....0..0..0....0..0..1
..0..1..1....0..0..0....1..0..0....0..1..0....1..1..1....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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