A030636 Numbers with 18 divisors.

180, 252, 288, 300, 396, 450, 468, 588, 612, 684, 700, 768, 800, 828, 882, 972, 980, 1044, 1100, 1116, 1280, 1300, 1332, 1452, 1476, 1548, 1568, 1575, 1692, 1700, 1792, 1900, 1908, 2028, 2124, 2156, 2178, 2196, 2205, 2300, 2412, 2420, 2450

Offset

1,1

Comments

Numbers of the form p^17, p*q^8 (A179668), p*q^2*r^2 (A179643) or p^2*q^5 (A179646), where p, q and r are distinct primes. - R. J. Mathar, Mar 01 2010

Links

R. J. Mathar, Table of n, a(n) for n = 1..1000

Mathematica

Select[Range[2500], DivisorSigma[0, #]==18&]  (* Harvey P. Dale, Feb 01 2011 *)

Prog

(PARI) is(n)=numdiv(n)==18 \\ Charles R Greathouse IV, Jun 19 2016

Crossrefs

Cf. A030635 (17 divs), A030637 (19 divs).

Sequence in context: A364976 A289056 A309380 * A378430 A350372 A179643

Adjacent sequences: A030633 A030634 A030635 * A030637 A030638 A030639

Keyword

nonn

Author

Jeff Burch

Extensions

882 inserted by N. J. A. Sloane, Mar 26 2007

Status

approved