%I A028260
%S A028260 1,4,6,9,10,14,15,16,21,22,24,25,26,33,34,35,36,38,39,40,46,49,51,54,
%T A028260 55,56,57,58,60,62,64,65,69,74,77,81,82,84,85,86,87,88,90,91,93,94,
%U A028260 95,96,100,104,106,111,115,118,119,121,122,123,126,129,132,133,134
%N A028260 Numbers n such that number of prime divisors of n (counted with multiplicity) 
               is even; Liouville function lambda(n) (A008836) is positive.
%C A028260 If n appears, p*n does not (p primes) . - Philippe DELEHAM (kolotoko(AT)wanadoo.fr), 
               Jun 10 2006
%C A028260 The product of any two members of the this sequence, or any two members 
               of the complement of this sequence (A026424) is a member of this 
               sequence. The product of a member of this sequence and a member of 
               A026424 is a member of A026424. The primitive elements of this sequence 
               are the semiprimes (A001358). - Franklin T. Adams-Watters (FrankTAW(AT)Netscape.net), 
               Nov 27 2006
%C A028260 A072978 is a subsequence. [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), 
               Sep 20 2008]
%C A028260 A066829(a(n)) = 0. [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), 
               Jun 26 2009]
%H A028260 T. D. Noe, <a href="b028260.txt">Table of n, a(n) for n=1..10000</a>
%F A028260 Numbers n such that A069089(n)=A023900(n) - Benoit Cloitre (benoit7848c(AT)orange.fr), 
               Apr 07 2002
%Y A028260 Cf. A008836, A026424.
%Y A028260 Cf. A001222, A001358.
%Y A028260 Cf. A145784. [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), 
               Oct 19 2008]
%Y A028260 Sequence in context: A120329 A123249 A010428 this_sequence A085155 A063762 
               A001358
%Y A028260 Adjacent sequences: A028257 A028258 A028259 this_sequence A028261 A028262 
               A028263
%K A028260 nonn,easy,nice
%O A028260 1,2
%A A028260 Dan Asimov (dan(AT)research.att.com)