A175749 Numbers with 40 divisors.

1680, 2160, 2640, 3024, 3120, 3240, 3696, 4080, 4368, 4536, 4560, 4752, 5520, 5616, 5670, 5712, 6000, 6160, 6384, 6864, 6960, 7128, 7280, 7344, 7440, 7680, 7728, 8208, 8424, 8880, 8910, 8976, 9520, 9744, 9840, 9936, 10032, 10320, 10368, 10416, 10530, 10608

Offset

1,1

Comments

Numbers of the forms p^39, p^19*q^1, p^9*q^3, p^7*q^4, p^9*q^1*r^1, p^4*q^3*r^1 (A179698), and p^4*q^1*r^1*s^1 (A179693), where p, q, r, and s are distinct primes.

Links

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

OEIS Wiki, Index entries for number of divisors

Formula

A000005(a(n))=40.

Mathematica

Select[Range[20000], DivisorSigma[0, #]==40&] (* Vladimir Joseph Stephan Orlovsky, May 06 2011 *)

Prog

(PARI) is(n)=numdiv(n)==40 \\ Charles R Greathouse IV, Jun 19 2016

Crossrefs

Cf. A175747, A175748.

Sequence in context: A093787 A258920 A268288 * A231548 A179693 A290704

Adjacent sequences: A175746 A175747 A175748 * A175750 A175751 A175752

Keyword

nonn

Author

Jaroslav Krizek, Aug 27 2010

Status

approved