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A224311
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Number of 3Xn 0..2 arrays with diagonals and rows unimodal and antidiagonals nondecreasing
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1
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27, 324, 1586, 5996, 20214, 61953, 174378, 454832, 1108958, 2547780, 5554847, 11564081, 23107746, 44519456, 83011127, 150287312, 264917825, 455762696, 766835415, 1264104630, 2044874898, 3250558135, 5083853932, 7831604260
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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) = (1/19160064)*n^12 + (1/1064448)*n^11 + (1507/43545600)*n^10 + (73/161280)*n^9 + (23603/2903040)*n^8 + (111/3584)*n^7 + (13023121/43545600)*n^6 + (130093/96768)*n^5 + (5619469/2177280)*n^4 + (54895/2688)*n^3 - (11456441/1663200)*n^2 + (205131/1540)*n - 196 for n>3
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EXAMPLE
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Some solutions for n=3
..1..2..0....2..1..1....0..0..0....0..2..1....1..0..0....2..2..1....2..0..0
..2..2..0....2..2..0....0..2..0....2..2..0....0..2..1....2..2..0....0..2..0
..2..2..2....2..0..0....2..0..0....2..1..1....2..2..1....2..2..0....2..1..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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