login
Numbers with a nonprime number of prime divisors (counted with multiplicity).
5

%I #10 Jun 19 2016 03:02:51

%S 1,2,3,5,7,11,13,16,17,19,23,24,29,31,36,37,40,41,43,47,53,54,56,59,

%T 60,61,64,67,71,73,79,81,83,84,88,89,90,96,97,100,101,103,104,107,109,

%U 113,126,127,131,132,135,136,137,139,140,144,149,150,151,152,156,157,160

%N Numbers with a nonprime number of prime divisors (counted with multiplicity).

%H G. C. Greubel, <a href="/A167175/b167175.txt">Table of n, a(n) for n = 1..1000</a>

%t Select[Range[200],!PrimeQ[PrimeOmega[#]]&] (* _Harvey P. Dale_, Apr 14 2013 *)

%o (PARI) is(n)=!isprime(bigomega(n)) \\ _Charles R Greathouse IV_, Jun 19 2016

%Y Cf. A001222, A063989, A141468.

%K nonn

%O 1,2

%A _Juri-Stepan Gerasimov_, Oct 29 2009

%E 86 replaced by 96, 112 and 124 removed, 147 replaced by 144, 153 removed - _R. J. Mathar_, Apr 14 2010