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A034884
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Numbers k such that k < d(k)^2, where d(k) = A000005(k).
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32
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2, 3, 4, 6, 8, 10, 12, 14, 15, 16, 18, 20, 24, 28, 30, 32, 36, 40, 42, 48, 54, 56, 60, 72, 80, 84, 90, 96, 108, 120, 126, 132, 140, 144, 168, 180, 192, 210, 216, 240, 252, 288, 300, 336, 360, 420, 480, 504, 540, 720, 840, 1260
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OFFSET
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1,1
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COMMENTS
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The deficient terms are 2, 3, 4, 8, 10, 14, 15, 16, 32; the first perfect or abundant number not listed is 66 = 2 * 3 * 11; the only term not 7-smooth is 132 = 2^2 * 3 * 11; the largest not divisible by 6 is 140 = 2^2 * 5 * 7. - Peter Munn, Sep 19 2021
The union of this sequence and A276734 has 74 total terms which are all k with floor(sqrt(k)) <= d(k). - Bill McEachen, Apr 07 2023
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LINKS
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MATHEMATICA
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Select[Range[1300], #<DivisorSigma[0, #]^2&] (* Harvey P. Dale, Apr 11 2014 *)
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PROG
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CROSSREFS
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KEYWORD
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nonn,fini,full
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AUTHOR
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EXTENSIONS
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Labos Elemer added the last three terms and observes that this sequence is now complete.
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STATUS
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approved
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