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A057561
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Size of the largest set encompassing no {x, 2x, 3x} contained in D(n) = the first n 3-smooth numbers {1, 2, 3, 4, 6, 8, 9, 12, 16, 18, 24, 27,...} (A003586).
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4
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1, 2, 2, 3, 4, 5, 5, 6, 7, 7, 8, 8, 9, 10, 11, 11, 12, 13, 13, 14, 14, 15, 16, 17, 17, 18, 18, 19, 20, 20, 21, 22, 22, 23, 24, 25
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OFFSET
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1,2
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COMMENTS
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This is the weakly triple-free analog of A157271.
A094708(n) = n - a(n)
Position of first n gives A004059(n).
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REFERENCES
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R. L. Graham et al., On extremal density theorems for linear forms, pp. 103-109 of H. Zassenhaus, editor, Number Theory and Algebra. Academic Press, NY, 1977.
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LINKS
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Table of n, a(n) for n=1..36.
S. R. Finch, Triple-Free Sets of Integers
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CROSSREFS
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Cf. A004059, A094708, A003586, A157271.
Sequence in context: A218445 A034137 A156351 * A064726 A210357 A057359
Adjacent sequences: A057558 A057559 A057560 * A057562 A057563 A057564
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane.
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EXTENSIONS
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Edited by Steven Finch, Feb 25 2009
Revised by N. J. A. Sloane, Jun 13 2012
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STATUS
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approved
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