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A337645
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a(1)=2; thereafter, a(n) = smallest number with at least two different prime factors that is missing from A336957 after A336957(n) has been found.
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4
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2, 6, 10, 10, 10, 10, 10, 10, 10, 18, 20, 20, 20, 20, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 36, 36, 36, 36, 44, 44, 44, 44, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 54
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refs;
listen;
history;
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OFFSET
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1,1
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COMMENTS
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The initial 2 is an exception. For n>2, A336957(n) is required to have at least two different prime factors.
It is conjectured that every number with at least two different prime factors will eventually appear in A336957.
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LINKS
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N. J. A. Sloane, Table of n, a(n) for n = 1..20000
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EXAMPLE
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A336957 begins 1, 2, 6, 15, 35, 14, with A336957(6)=14. At that point 10 is the smallest legal candidate that has not yet appeared, so a(6) = 10.
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CROSSREFS
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Cf. A336957, A338052, A338058.
Sequence in context: A122882 A136700 A054645 * A225271 A050425 A030405
Adjacent sequences: A337642 A337643 A337644 * A337646 A337647 A337648
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KEYWORD
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nonn
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AUTHOR
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Scott R. Shannon and N. J. A. Sloane, Sep 25 2020; corrected Oct 11 2020
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STATUS
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approved
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