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A086920
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Smallest k such that n times concatenation of k with itself followed by a 1 is a prime, or 0 if no such number exists.
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7
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1, 3, 2, 3, 3, 3, 3, 30, 6, 4, 5, 5, 25, 42, 17, 19, 2, 1, 7, 6, 6, 1, 50, 29, 138, 153, 4, 45, 54, 7, 15, 9, 78, 147, 95, 58, 102, 18, 3, 115, 54, 6, 46, 9, 24, 64, 183, 120, 3, 33, 112, 46, 105, 4, 279, 122, 68, 75, 3, 22, 294, 56, 92, 76, 6, 19, 94, 71, 12, 75, 30, 16, 78, 320, 33
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| Conjecture: no term is zero.
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EXAMPLE
| a(3) = 2 as 2221 is a prime. a(4) = 3 as 33331 is a prime but 11111 and 22221 are not.
a(8) = 30 and the prime arising is 30303030303030301.
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CROSSREFS
| Cf. A087604, A087605, A087606, A087607, A087608, A087609.
Cf. A086923.
Cf. A086766.
Sequence in context: A098726 A065801 A205237 * A117451 A130970 A144733
Adjacent sequences: A086917 A086918 A086919 * A086921 A086922 A086923
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KEYWORD
| base,nonn
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AUTHOR
| Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Sep 18 2003
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EXTENSIONS
| More terms from Ray G. Opao (1260(AT)email.com), Apr 15 2004
More terms from David Wasserman (wasserma(AT)spawar.navy.mil), Apr 12 2005
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