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A137491
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Numbers with 28 divisors.
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5
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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
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OFFSET
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1,1
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COMMENTS
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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
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LINKS
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T. D. Noe, Table of n, a(n) for n = 1..1000
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FORMULA
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A000005(a(n)) = 28.
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MAPLE
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with(numtheory): A137491:=n->`if`(tau(n)=28, n, NULL): seq(A137491(n), n=1..15000); # Wesley Ivan Hurt, Sep 18 2014
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MATHEMATICA
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Select[Range[30000], DivisorSigma[0, #]==28&] (* Vladimir Joseph Stephan Orlovsky, May 06 2011 *)
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PROG
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(PARI) is(n)=numdiv(n)==28 \\ Charles R Greathouse IV, Jun 19 2016
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CROSSREFS
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Cf. A030513-A030516, A030626, A030627, A030634-A030638, A005179, A003680, A096932, A061286, A061283.
Sequence in context: A167780 A316338 A257417 * A179672 A348523 A158412
Adjacent sequences: A137488 A137489 A137490 * A137492 A137493 A137494
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KEYWORD
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nonn
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AUTHOR
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R. J. Mathar, Apr 22 2008
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STATUS
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approved
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