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Search: id:A104239
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| A104239 |
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Number of distinct prime factors of 135...(2n-1) (concatenation of n odd numbers). |
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+0
1
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| 0, 1, 2, 2, 2, 3, 2, 5, 3, 1, 4, 3, 3, 2, 3, 1, 5, 5, 7, 4, 5, 5, 4, 5, 5, 2, 4, 5, 4, 6, 5, 3, 7, 1, 4, 4, 3, 4, 3, 6, 5, 7, 5, 7, 8, 4, 7, 7, 1, 6
(list; graph; listen)
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OFFSET
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1,3
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COMMENT
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Interestingly, 135791113151719 is prime.
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LINKS
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Eric Weisstein's World of Mathematics, Consecutive Number sequences
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EXAMPLE
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The number of distinct prime factors of 13 is 1 (a prime) - the second term in the sequence.
The number of distinct prime factors of 135 is 2 - the third term in the sequence.
The number of distinct prime factors of 1357 is 2 - the fourth term in the sequence.
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CROSSREFS
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Cf. A001221, A048847.
Sequence in context: A121611 A046798 A157231 this_sequence A058614 A058726 A132321
Adjacent sequences: A104236 A104237 A104238 this_sequence A104240 A104241 A104242
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KEYWORD
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nonn,base
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AUTHOR
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Parthasarathy Nambi (PachaNambi(AT)yahoo.com), Apr 16 2005
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EXTENSIONS
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Corrected and extended by Frank Adams-Watters (FrankTAW(AT)Netscape.net), Sep 01 2006
Edited by N. J. A. Sloane (njas(AT)research.att.com), May 21 2008 at the suggestion of R. J. Mathar
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