login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A051270 Numbers that are divisible by exactly 5 different primes. 22
2310, 2730, 3570, 3990, 4290, 4620, 4830, 5460, 5610, 6006, 6090, 6270, 6510, 6630, 6930, 7140, 7410, 7590, 7770, 7854, 7980, 8190, 8580, 8610, 8778, 8970, 9030, 9240, 9282, 9570, 9660, 9690, 9870, 10010, 10230, 10374, 10626, 10710, 10920, 11130 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

EXAMPLE

2730 = 2*3*5*7*13 is the first nontrivial 5-prime factor number following the 5th primorial, 2310 = 2*3*5*7*11.

MATHEMATICA

lst={}; Do[If[Length[FactorInteger[n]]==5, (*Print[n]; *)AppendTo[lst, n]], {n, 3*10^4}]; lst (* Vladimir Joseph Stephan Orlovsky, Aug 21 2008 *)

Select[Range[12000], PrimeNu[#]==5&] (* Harvey P. Dale, Feb 13 2012 *)

PROG

(PARI) is(n)=omega(n)==5 \\ Charles R Greathouse IV, Apr 29 2015

(Python)

from sympy import primefactors

print [n for n in xrange(2, 20001) if len(primefactors(n))==5] # Indranil Ghosh, Apr 06 2017

CROSSREFS

Cf. A000961, A007774, A000977, A002110, A033992, A033993.

Cf. A046303 (a subsequence). - Michel Marcus, Apr 06 2017

Sequence in context: A060231 A285487 A285744 * A046387 A136154 A258360

Adjacent sequences:  A051267 A051268 A051269 * A051271 A051272 A051273

KEYWORD

nonn

AUTHOR

Labos Elemer

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 24 19:49 EDT 2019. Contains 322446 sequences. (Running on oeis4.)