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A034884 n < d(n)^2, d() = number of divisors. 31
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

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

LINKS

Table of n, a(n) for n=1..52.

MATHEMATICA

Select[Range[1300], #<DivisorSigma[0, #]^2&] (* Harvey P. Dale, Apr 11 2014 *)

PROG

(PARI) isok(n) = (n < numdiv(n)^2) \\ Michel Marcus, Jun 07 2013

CROSSREFS

Cf. A000005, A035033, A035034, A035035, A033950, A036763.

Sequence in context: A336367 A064377 A175495 * A137291 A032954 A158023

Adjacent sequences:  A034881 A034882 A034883 * A034885 A034886 A034887

KEYWORD

nonn,fini,full

AUTHOR

Erich Friedman

EXTENSIONS

Labos Elemer added the last three terms and observes that this sequence is now complete.

STATUS

approved

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Last modified October 22 01:48 EDT 2021. Contains 348160 sequences. (Running on oeis4.)