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A030634 Numbers with 16 divisors. 18

%I #27 Sep 08 2022 08:44:50

%S 120,168,210,216,264,270,280,312,330,378,384,390,408,440,456,462,510,

%T 520,546,552,570,594,616,640,680,690,696,702,714,728,744,750,760,770,

%U 798,858,870,888,896,910,918,920,930,945,952,966,984,1000

%N Numbers with 16 divisors.

%C Numbers of the form p^15 (subset of A010803), p*q^7, p*q*r^3 or p^3*q^3, or p*q*r*s, where p, q, r and s are distinct primes. - _R. J. Mathar_, Mar 01 2010

%H R. J. Mathar, <a href="/A030634/b030634.txt">Table of n, a(n) for n = 1..1000</a>

%H Jérôme Germoni, <a href="http://images.math.cnrs.fr/Nombres-a-huit-diviseurs.html">Nombres à huit diviseurs</a>, Images des Mathématiques, CNRS, 2017 (in French).

%t Select[Range[3000],DivisorSigma[0,#]==16&] (* _Vladimir Joseph Stephan Orlovsky_, May 05 2011 *)

%o (PARI) is(n)=numdiv(n)==16 \\ _Charles R Greathouse IV_, Jun 19 2016

%o (Magma) [n: n in [1..1000] | DivisorSigma(0, n) eq 16]; // _Vincenzo Librandi_, Oct 05 2017

%Y Cf. A030626, A030631, A030632, A030633.

%K nonn

%O 1,1

%A _Jeff Burch_

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Last modified April 18 15:48 EDT 2024. Contains 371780 sequences. (Running on oeis4.)