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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A177871 Numbers n such that bigomega(n)^omega(n) > n. 1
60, 120, 210, 420, 840, 1260, 1680, 2310, 2730, 3360, 4620, 5460, 6930, 7140, 9240, 10920, 13860, 14280, 15960, 16380, 18480, 21840, 27720, 28560, 30030, 31920, 32760, 36960, 39270, 43680, 43890, 46410, 55440, 57120, 60060, 73920, 78540, 87360, 87780, 90090, 92820, 103740, 106260 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

bigomega(n) or Omega(n) is the number of prime divisors of n (counted with  multiplicity): A001222, and omega(n) is the number of distinct primes dividing n: A001221.

REFERENCES

J.-M. De Koninck, Ces nombres qui nous fascinent, Entry 60, p. 22, Ellipses, Paris 2008.

LINKS

Donovan Johnson, Table of n, a(n) for n = 1..500

EXAMPLE

120 is in the sequence because bigomega(120) = 5, omega(120) = 3, and 5^3 = 125 > 120.

MAPLE

with(numtheory): for n from 1 to 200000 do:if bigomega(n)^ nops(factorset(n))>

  n then printf(`%d, `, n):else fi:od:

MATHEMATICA

Select[Range[2, 10^5], PrimeOmega[#]^PrimeNu[#] > # &] (* From Alonso del Arte, Dec 13 2010 *)

CROSSREFS

Sequence in context: A098136 A060793 A169823 * A252953 A309315 A275339

Adjacent sequences:  A177868 A177869 A177870 * A177872 A177873 A177874

KEYWORD

nonn

AUTHOR

Michel Lagneau, Dec 13 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 | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 17 08:36 EDT 2019. Contains 328107 sequences. (Running on oeis4.)