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A034884
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n < d(n)^2, d() = number of divisors.
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31
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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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See comment in A175495. - Vladimir Shevelev, May 07 2013
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
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LINKS
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Table of n, a(n) for n=1..52.
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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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(PARI) isok(n) = (n < numdiv(n)^2) \\ Michel Marcus, Jun 07 2013
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CROSSREFS
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Cf. A000005, A035033, A035034, A035035, A033950, A036763.
Sequence in context: A336367 A064377 A175495 * A137291 A032954 A158023
Adjacent sequences: A034881 A034882 A034883 * A034885 A034886 A034887
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KEYWORD
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nonn,fini,full
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AUTHOR
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Erich Friedman
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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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