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A255771
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Number of distinct prime factors of A220294(n).
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4
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1, 1, 1, 2, 2, 1, 2, 2, 4, 2, 2
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history;
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OFFSET
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0,4
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COMMENTS
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These are the first differences of A255770.
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REFERENCES
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Arthur Engel, Problem-Solving Strategies, Springer, 1998, pages 121-122 (E3, said to be a "recent competition problem from the former USSR").
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LINKS
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EXAMPLE
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A220294(4) = 193*22253377 so a(4) = 2.
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CROSSREFS
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KEYWORD
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nonn,hard,more
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AUTHOR
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EXTENSIONS
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a(9) was found in 2008 by Geoffrey Reynolds. a(10) was found by Anders Björn and Hans Riesel. - Arkadiusz Wesolowski, Aug 02 2016
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STATUS
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approved
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