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A137491 Numbers with 28 divisors. 5
960, 1344, 1728, 2112, 2240, 2496, 3264, 3520, 3648, 4160, 4416, 4928, 5440, 5568, 5824, 5832, 5952, 6080, 7104, 7290, 7360, 7616, 7872, 8000, 8256, 8512, 9024, 9152, 9280, 9920, 10176, 10206, 10304, 11328, 11712, 11840, 11968, 12864, 12992, 13120 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Maple implementation: see A030513.

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

LINKS

T. D. Noe, Table of n, a(n) for n = 1..1000

FORMULA

A000005(a(n)) = 28.

MAPLE

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

MATHEMATICA

Select[Range[30000], DivisorSigma[0, #]==28&] (* Vladimir Joseph Stephan Orlovsky, May 06 2011 *)

PROG

(PARI) is(n)=numdiv(n)==28 \\ Charles R Greathouse IV, Jun 19 2016

CROSSREFS

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

Sequence in context: A167780 A316338 A257417 * A179672 A158412 A247723

Adjacent sequences:  A137488 A137489 A137490 * A137492 A137493 A137494

KEYWORD

nonn

AUTHOR

R. J. Mathar, Apr 22 2008

STATUS

approved

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Last modified October 18 08:08 EDT 2019. Contains 328146 sequences. (Running on oeis4.)