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A068696
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Number of primes that are a concatenation nk of n and k for values of k from 1 to n.
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2
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1, 0, 1, 2, 1, 1, 2, 1, 1, 4, 1, 1, 3, 1, 3, 3, 2, 2, 5, 2, 3, 5, 3, 4, 3, 4, 5, 3, 3, 4, 5, 3, 7, 4, 7, 5, 5, 5, 7, 6, 6, 7, 6, 5, 5, 7, 5, 4, 7, 6, 3, 6, 4, 10, 5, 8, 8, 9, 6, 8, 9, 6, 10, 7, 8, 6, 7, 8, 8, 9, 6, 9, 8, 7, 12, 8, 8, 9, 8, 7, 9, 13, 8, 8, 12, 10, 11, 13, 8, 9, 11, 9, 11, 15, 8, 12, 13, 12
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,4
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COMMENTS
| Conjecture: a(2) is the only 0 in this sequence.
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EXAMPLE
| a(33)= 7 as we get primes 331, 337, 3313, 3319, 3323, 3329, 3331, for seven values of k i.e. k = 1, 7, 13, 19, 23, 29, 31. a(20) = 2, the primes are 2011 and 2017 (2003 doesn't count).
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CROSSREFS
| Sequence in context: A152198 A159255 A035693 * A133009 A186972 A053734
Adjacent sequences: A068693 A068694 A068695 * A068697 A068698 A068699
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KEYWORD
| base,easy,nonn
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AUTHOR
| Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Mar 03 2002
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EXTENSIONS
| More terms from Eli McGowan (ejmcgowa(AT)mail.lakeheadu.ca), May 06 2002
Corrected and extended by Jason Earls (zevi_35711(AT)yahoo.com), Sep 06 2002
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