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A068317 Numbers n such that n*tau(n) > omega(n)*prime(n) where tau(n) is the number of divisors of n and omega(n) the number of distinct prime factors of n. 1
1, 2, 3, 4, 8, 9, 16, 24, 27, 32, 36, 48, 64, 72, 96, 108, 128, 144, 160, 180, 192, 216, 240, 256, 288, 320, 324, 360, 384, 400, 432, 480, 504, 512, 540, 576, 600, 640, 648, 672, 720, 756, 768, 792, 800, 840, 864, 896, 900, 936, 960, 972, 1000, 1008, 1024 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

There are very few odd terms in the sequence: 1, 3, 9, 27, 30375, 33075,...

LINKS

Ivan Neretin, Table of n, a(n) for n = 1..10000

MATHEMATICA

Select[Range[1040], #*DivisorSigma[0, #] > PrimeNu[#]*Prime[#] &] (* Ivan Neretin, Mar 16 2017 *)

PROG

(PARI) for(n=1, 1000, if(numdiv(n)*n>omega(n)*prime(n), print1(n, ", ")))

CROSSREFS

Sequence in context: A078829 A045583 A045608 * A074311 A076382 A006899

Adjacent sequences:  A068314 A068315 A068316 * A068318 A068319 A068320

KEYWORD

easy,nonn

AUTHOR

Benoit Cloitre, Feb 26 2002

STATUS

approved

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Last modified September 20 18:52 EDT 2019. Contains 327245 sequences. (Running on oeis4.)