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A266473
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Number of 6Xn binary arrays with rows and columns lexicographically nondecreasing and column sums nonincreasing.
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1
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7, 29, 147, 794, 4074, 18808, 77320, 285494, 959672, 2975483, 8605341, 23428725, 60497931, 149066593, 352233950, 801471439, 1762213254, 3755124007, 7774777259, 15675004492, 30833594755, 59276323572, 111542905766, 205731574732
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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) = (1/121645100408832000)*n^19 + (1/914624815104000)*n^18 + (37/533531142144000)*n^17 + (89/31384184832000)*n^16 + (1039/12553673932800)*n^15 + (116807/62768369664000)*n^14 + (3153461/94152554496000)*n^13 + (511019/1034643456000)*n^12 + (57504877/9656672256000)*n^11 + (48689987/877879296000)*n^10 + (475429693/1207084032000)*n^9 + (2471183497/1207084032000)*n^8 + (117295069721/23538138624000)*n^7 + (79279038437/3362591232000)*n^6 + (2282457077/12108096000)*n^5 - (6773798653/40864824000)*n^4 + (20107095509/9648639000)*n^3 - (10497092849/7718911200)*n^2 + (607842269/116396280)*n + 1
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EXAMPLE
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Some solutions for n=4
..0..0..1..1....0..0..0..1....0..0..0..1....0..0..1..1....0..0..0..1
..0..1..0..0....1..1..1..0....0..0..1..0....0..1..1..1....0..0..1..0
..0..1..0..1....1..1..1..0....0..0..1..0....1..0..1..1....0..1..1..0
..1..0..0..1....1..1..1..1....0..1..0..0....1..1..0..0....1..0..0..0
..1..0..1..0....1..1..1..1....1..0..0..1....1..1..0..0....1..0..0..0
..1..1..1..0....1..1..1..1....1..1..0..0....1..1..1..1....1..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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