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A137487 Numbers with 24 divisors. 4

%I #14 May 04 2018 08:49:50

%S 360,420,480,504,540,600,630,660,672,756,780,792,864,924,936,990,1020,

%T 1050,1056,1092,1120,1140,1152,1170,1176,1188,1224,1248,1350,1368,

%U 1380,1386,1400,1404,1428,1470,1500,1530,1540,1596,1632,1638,1650,1656,1710

%N Numbers with 24 divisors.

%C Maple implementation: see A030513.

%C Numbers of the form p^23, p^2*q^7, p*q^2*r^3 (like 360, 504), p*q*r^5 (like 480, 672), p*q*r*s^2 (like 420, 660), p^3*q^5 (like 864) or p*q^11, where p, q, r and s are distinct primes. - _R. J. Mathar_, Mar 01 2010

%H T. D. Noe, <a href="/A137487/b137487.txt">Table of n, a(n) for n = 1..1000</a>

%F A000005(a(n))=24.

%t Select[Range[3000],DivisorSigma[0,#]==24&] (* _Vladimir Joseph Stephan Orlovsky_, May 05 2011 *)

%o (PARI) is(n)=numdiv(n)==24 \\ _Charles R Greathouse IV_, Jun 19 2016

%Y Cf. A030513-A030516, A030626, A030627, A030634-A030638, A005179, A003680, A096932, A061286, A061283.

%K nonn

%O 1,1

%A _R. J. Mathar_, Apr 22 2008

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Last modified March 19 04:58 EDT 2024. Contains 370952 sequences. (Running on oeis4.)