A030634 Numbers with 16 divisors.

120, 168, 210, 216, 264, 270, 280, 312, 330, 378, 384, 390, 408, 440, 456, 462, 510, 520, 546, 552, 570, 594, 616, 640, 680, 690, 696, 702, 714, 728, 744, 750, 760, 770, 798, 858, 870, 888, 896, 910, 918, 920, 930, 945, 952, 966, 984, 1000

Offset: 1

Author

Jeff Burch

Keywords

• nonn

Comments

Numbers of the form p^15 (subset of A010803), p*q^7, p*q*r^3 or p^3*q^3, or p*q*r*s, where p, q, r and s are distinct primes. - R. J. Mathar, Mar 01 2010

Links

• R. J. Mathar, Table of n, a(n) for n = 1..1000
• Jérôme Germoni, Nombres à huit diviseurs, Images des Mathématiques, CNRS, 2017 (in French).

Crossrefs

Cf. A030626, A030631, A030632, A030633.

Programs

Magma

[n: n in [1..1000] | DivisorSigma(0, n) eq 16]; // Vincenzo Librandi, Oct 05 2017

Mathematica

Select[Range[3000],DivisorSigma[0,#]==16&] (* Vladimir Joseph Stephan Orlovsky, May 05 2011 *)

PARI

is(n)=numdiv(n)==16 \\ Charles R Greathouse IV, Jun 19 2016