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A327829 Squarefree numbers with a prime number of prime factors. 1

%I #29 Mar 06 2021 06:00:11

%S 6,10,14,15,21,22,26,30,33,34,35,38,39,42,46,51,55,57,58,62,65,66,69,

%T 70,74,77,78,82,85,86,87,91,93,94,95,102,105,106,110,111,114,115,118,

%U 119,122,123,129,130,133,134,138,141,142,143,145,146,154,155,158,159,161

%N Squarefree numbers with a prime number of prime factors.

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

%H Amiram Eldar, <a href="/A327829/b327829.txt">Table of n, a(n) for n = 1..10000</a>

%F A006881 UNION A007304 UNION A046387 UNION A123321 UNION .... - _R. J. Mathar_, Oct 13 2019

%t Select[Range@ 161, And[SquareFreeQ@ #, PrimeQ@ PrimeNu@ #] &] (* _Michael De Vlieger_, Sep 29 2019 *)

%o (PARI) isok(n) = issquarefree(n) && isprime(omega(n)); \\ _Michel Marcus_, Sep 27 2019

%Y Subsequence of A120944.

%Y A006881, A007304, A046387 are subsequences.

%Y A046386, A067885 are not subsequences.

%K nonn

%O 1,1

%A _Sebastian F. Orellana_, Sep 26 2019

%E Corrected and extended by _Michel Marcus_, Sep 27 2019

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Last modified March 28 10:55 EDT 2024. Contains 371241 sequences. (Running on oeis4.)