A327829 Squarefree numbers with a prime number of prime factors.

6, 10, 14, 15, 21, 22, 26, 30, 33, 34, 35, 38, 39, 42, 46, 51, 55, 57, 58, 62, 65, 66, 69, 70, 74, 77, 78, 82, 85, 86, 87, 91, 93, 94, 95, 102, 105, 106, 110, 111, 114, 115, 118, 119, 122, 123, 129, 130, 133, 134, 138, 141, 142, 143, 145, 146, 154, 155, 158, 159, 161

Offset

1,1

Comments

210 is the first integer in A120944 but not here: it has 4 prime factors.

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Formula

A006881 UNION A007304 UNION A046387 UNION A123321 UNION .... - R. J. Mathar, Oct 13 2019

Mathematica

Select[Range@ 161, And[SquareFreeQ@ #, PrimeQ@ PrimeNu@ #] &] (* Michael De Vlieger, Sep 29 2019 *)

Prog

(PARI) isok(n) = issquarefree(n) && isprime(omega(n)); \\ Michel Marcus, Sep 27 2019

Crossrefs

Subsequence of A120944.

A006881, A007304, A046387 are subsequences.

A046386, A067885 are not subsequences.

Sequence in context: A080365 A000469 A120944 * A052053 A276818 A325259

Adjacent sequences: A327826 A327827 A327828 * A327830 A327831 A327832

Keyword

nonn

Author

Sebastian F. Orellana, Sep 26 2019

Extensions

Corrected and extended by Michel Marcus, Sep 27 2019

Status

approved