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A221621
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Number of nX6 arrays with each row a permutation of 1..6 having at least as many downsteps as the preceding row
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1
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720, 353654, 148700748, 57614883627, 21241004664348, 7575106427737240, 2638115823321645192, 902542985526634773509, 304529313276100670030616, 101620178879261858322711162, 33604296810830843896378600020
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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) = 720*a(n-1) -164746*a(n-2) +12686988*a(n-3) -321204409*a(n-4) +605003244*a(n-5) -296321796*a(n-6)
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EXAMPLE
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Some solutions for n=3
..4..1..2..5..3..6....4..1..2..5..3..6....4..1..2..5..3..6....4..1..2..5..3..6
..1..4..6..3..5..2....3..1..2..5..4..6....4..1..2..6..5..3....3..1..5..4..6..2
..2..1..4..3..6..5....3..6..2..5..4..1....5..4..6..3..1..2....2..1..4..3..6..5
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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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