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A064040 Number of distinct prime divisors of n is a prime. 4
6, 10, 12, 14, 15, 18, 20, 21, 22, 24, 26, 28, 30, 33, 34, 35, 36, 38, 39, 40, 42, 44, 45, 46, 48, 50, 51, 52, 54, 55, 56, 57, 58, 60, 62, 63, 65, 66, 68, 69, 70, 72, 74, 75, 76, 77, 78, 80, 82, 84, 85, 86, 87, 88, 90, 91, 92, 93, 94, 95, 96, 98, 99, 100, 102, 104, 105 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Below 210 this sequence and A024619 are identical.

LINKS

Harry J. Smith, Table of n, a(n) for n = 1..1000

EXAMPLE

210 = 2*3*5*7 has 4 prime factors, hence it is not here, but it is part of A024619.

PROG

(PARI) n=0; for (m=1, 10^9, if (isprime(omega(m)), write("b064040.txt", n++, " ", m); if (n==1000, break))) \\ Harry J. Smith, Sep 06 2009

(PARI) is(n)=isprime(omega(n)) \\ Charles R Greathouse IV, Sep 18 2015

CROSSREFS

Cf. A024619, A000977, A033992, A007774, A033993, A051270, A063989.

Sequence in context: A329367 A325265 A105642 * A168638 A024619 A335080

Adjacent sequences:  A064037 A064038 A064039 * A064041 A064042 A064043

KEYWORD

nonn,easy

AUTHOR

Lior Manor Aug 23 2001

EXTENSIONS

Edited by Charles R Greathouse IV, Mar 18 2010

STATUS

approved

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Last modified July 4 14:51 EDT 2020. Contains 335448 sequences. (Running on oeis4.)