A137491 Numbers with 28 divisors.

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

Offset

1,1

Comments

Maple implementation: see A030513.

Numbers of the form p^27 (subset of A122968), p*q^13, p*q*r^6 (A179672) or p^3*q^6 (A179694), 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 A348523 A158412

Adjacent sequences: A137488 A137489 A137490 * A137492 A137493 A137494

Keyword

nonn

Author

R. J. Mathar, Apr 22 2008

Status

approved