login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A172443 Numbers with exactly 64 divisors. 1
7560, 9240, 10920, 11880, 13440, 14040, 14280, 15960, 16632, 17160, 17280, 18360, 19320, 19656, 20520, 20790, 21000, 21120, 22440, 24024, 24192, 24360, 24570, 24840, 24960, 25080, 25704, 26040, 26520, 27000, 28728, 29568, 29640, 30030, 30360, 30888, 31080 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The first squarefree term of this sequence is the primorial a(34) = 30030.

Almost all terms of this sequence (in the sense of having relative density 1) are squarefree, that is in our case, the product of six distinct primes = A067885. - Charles R Greathouse IV, Aug 27 2021

LINKS

David A. Corneth, Table of n, a(n) for n = 1..10000

EXAMPLE

10920 has 64 divisors.

MATHEMATICA

Select[Range[100000], DivisorSigma[0, #]==64&]

PROG

(PARI) is(n) = numdiv(n) == 64 \\ David A. Corneth, Aug 27 2021

(Python)

from sympy import divisor_count

def ok(n): return divisor_count(n) == 64

print(list(filter(ok, range(31100)))) # Michael S. Branicky, Aug 27 2021

CROSSREFS

Cf. A067885.

Sequence in context: A210171 A234987 A157322 * A190108 A308913 A145313

Adjacent sequences:  A172440 A172441 A172442 * A172444 A172445 A172446

KEYWORD

nonn,easy

AUTHOR

Harvey P. Dale, Nov 20 2010

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified July 6 15:57 EDT 2022. Contains 355111 sequences. (Running on oeis4.)