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A068669
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Noncomposite numbers in which every substring is noncomposite.
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7
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1, 2, 3, 5, 7, 11, 13, 17, 23, 31, 37, 53, 71, 73, 113, 131, 137, 173, 311, 313, 317, 373, 1373, 3137
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| It is easy to see that this sequence is complete - the only potential 5-digit candidate 31373 is not prime. - Tanya Khovanova (tanyakh(AT)yahoo.com), Dec 09 2006
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EXAMPLE
| 137 is a member as all the substrings, i.e. 1, 3, 7, 13, 37, 137, are noncomposite.
All substrings of 3137 are noncomposite numbers: 1, 3, 7, 13, 37, 137, 313, 3137. - Jaroslav Krizek, Dec 25 2011
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CROSSREFS
| Cf. A012884, A062115, A202262.
Sequence in context: A160337 A190222 A012884 * A100553 A175584 A152245
Adjacent sequences: A068666 A068667 A068668 * A068670 A068671 A068672
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KEYWORD
| base,nonn,fini,full
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AUTHOR
| Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Mar 02 2002
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EXTENSIONS
| 1 added following a redefinition by Jaroslav Krizek. - R. J. Mathar, Jan 20 2012
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