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A030230 Numbers n such that number of distinct primes dividing n is odd. +0
3
2, 3, 4, 5, 7, 8, 9, 11, 13, 16, 17, 19, 23, 25, 27, 29, 30, 31, 32, 37, 41, 42, 43, 47, 49, 53, 59, 60, 61, 64, 66, 67, 70, 71, 73, 78, 79, 81, 83, 84, 89, 90, 97, 101, 102, 103, 105, 107, 109, 110, 113, 114, 120, 121, 125, 126, 127, 128, 130, 131, 132, 137, 138, 139, 140, 149 (list; graph; listen)
OFFSET

1,1

COMMENT

GCD[A008472(a[n]), A007947(a[n])]>1; see A014963. - Labos E. (labos(AT)ana.sote.hu), Mar 26 2003

LINKS

T. D. Noe, Table of n, a(n) for n=1..1000

FORMULA

n such that sum(d|n, mu(d)*tau(d))=(-1)^omega(n)=-1 where mu(d)=A008683(d), tau(d)=A000005(d) and omega(d)=A001221(d). - Benoit Cloitre, Dec 08 2002

n such that sum(d|n, mu(d)*tau(d))=(-1)^omega(n)=-1 where mu(d)=A008683(d), tau(d)=A000005(d) and omega(d)=A001221(d). n such that A023900(n)<0 - Benoit Cloitre, Dec 08 2002

CROSSREFS

Cf. A030231.

Sequence in context: A133811 A119314 A014567 this_sequence A089352 A086486 A071139

Adjacent sequences: A030227 A030228 A030229 this_sequence A030231 A030232 A030233

KEYWORD

nonn,easy,nice

AUTHOR

David W. Wilson (davidwwilson(AT)comcast.net)

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Last modified December 17 23:40 EST 2009. Contains 171025 sequences.


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