

A075592


Numbers n such that number of distinct prime divisors of n is a divisor of n.


13



2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 16, 17, 18, 19, 20, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 34, 36, 37, 38, 40, 41, 42, 43, 44, 46, 47, 48, 49, 50, 52, 53, 54, 56, 58, 59, 60, 61, 62, 64, 66, 67, 68, 71, 72, 73, 74, 76, 78, 79, 80, 81, 82, 83, 84, 86, 88, 89, 90
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OFFSET

1,1


COMMENTS

Numbers n such that omega(n) divides n.
The asymptotic density of this sequence is 0 (Cooper and Kennedy, 1989).  Amiram Eldar, Jul 10 2020


LINKS



MATHEMATICA

Select[Range[2, 100], Divisible[#, Length[Select[Divisors[#], PrimeQ]]]&] (* Harvey P. Dale, Mar 17 2011 *)


PROG

(R) library(gmp); omega<function(x) length(unique(as.numeric(factorize(x))))
(PARI) isok(n) = iferr(!(n % omega(n)), E, 0); \\ Michel Marcus, Oct 06 2017


CROSSREFS

Different from A070776: 78 belongs to this sequence but not to A070776.


KEYWORD

easy,nonn


AUTHOR



EXTENSIONS



STATUS

approved



