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 A137491 Numbers with 28 divisors. 5

%I

%S 960,1344,1728,2112,2240,2496,3264,3520,3648,4160,4416,4928,5440,5568,

%T 5824,5832,5952,6080,7104,7290,7360,7616,7872,8000,8256,8512,9024,

%U 9152,9280,9920,10176,10206,10304,11328,11712,11840,11968,12864,12992,13120

%N Numbers with 28 divisors.

%C Maple implementation: see A030513.

%C Numbers of the form p^27 (subset of A122968), p*q^13, p*q*r^6 (like 960, 1344, 2112) or p^3*q^6 (like 1728, 5832, 8000, third powers of A054753), where p, q and r are distinct primes. - _R. J. Mathar_, Mar 01 2010

%H T. D. Noe, <a href="/A137491/b137491.txt">Table of n, a(n) for n = 1..1000</a>

%F A000005(a(n)) = 28.

%p with(numtheory): A137491:=n->`if`(tau(n)=28,n,NULL): seq(A137491(n), n=1..15000); # _Wesley Ivan Hurt_, Sep 18 2014

%t Select[Range[30000],DivisorSigma[0,#]==28&] (* _Vladimir Joseph Stephan Orlovsky_, May 06 2011 *)

%o (PARI) is(n)=numdiv(n)==28 \\ _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 January 29 08:04 EST 2020. Contains 331337 sequences. (Running on oeis4.)