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A002967
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Egyptian fractions: number of solutions of 1 = 1/x_1 + ... + 1/x_n in positive integers.
(Formerly M4745)
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9
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OFFSET
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1,3
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COMMENTS
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Solutions differing only in the order of the x_i are counted as distinct.
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REFERENCES
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R. K. Guy, Unsolved Problems in Number Theory, D11.
D. Singmaster, "The number of representations of one as a sum of unit fractions," unpublished manuscript, 1972.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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EXAMPLE
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For n=3 the 10 solutions are {2,3,6} (6 ways), {2,4,4} (3 ways), {3,3,3} (1 way).
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CROSSREFS
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KEYWORD
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nonn,nice,hard,more
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AUTHOR
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EXTENSIONS
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a(8) from John Dethridge, Jan 11 2004
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STATUS
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approved
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