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A181899
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Largest divisor of n!/4 which is less than sqrt(n!)/2.
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0
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2, 5, 12, 35, 96, 288, 945, 3150, 10800, 39312, 147420, 571536, 2286144, 9424800, 39984000, 174283200, 779688000, 3573570000, 16761064320, 80379048750, 393826406400, 1969132032000, 10040487256800, 52174220175000, 276080056560000, 1486750296281250
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OFFSET
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4,1
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COMMENTS
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Comment from A038202: Let f=n!/4 and let a(n) be the largest divisor of f such that a(n) < sqrt(f). Then A038202(n) = f/a(n) - a(n). The greatest k such that n!+k^2 is a square is f-1. The number of k for which n!+k^2 is a square is A038548(f). - T. D. Noe, Nov 02 2004
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LINKS
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MATHEMATICA
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Table[f = n!/4; Select[Divisors[f], # <= Sqrt[f] &][[-1]], {n, 4, 20}]
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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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