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A123487
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Smallest prime q such that (q^p-1)/(q-1) is prime, where p = Prime[n]; or 0 if no such prime q exists.
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3
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2, 2, 2, 2, 5, 2, 2, 2, 113, 151, 2, 61, 53, 89, 5, 307, 19, 2, 491, 3, 11, 271, 41, 2, 271, 359, 3, 2, 79, 233, 2, 7, 13, 11, 5, 29, 71, 139, 127, 139, 2003, 5, 743, 673, 593, 383, 653, 661, 251, 6389, 2833, 223, 163, 37, 709, 131, 41, 2203, 941, 2707, 13, 1283, 383
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Corresponding primes (q^p-1)/(q-1), where prime q = a(n) and p = Prime[n], are listed in A123488[n] = {3,7,31,127,12207031,8191,131071,524287,1484520425576434196455942238665054573307722183,...}. a(n) coincides with A066180[n] when A066180[n] is prime or 0.
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CROSSREFS
| Cf. A123488, A066180, A084732.
Sequence in context: A130086 A084731 A066180 * A130325 A154097 A107604
Adjacent sequences: A123484 A123485 A123486 * A123488 A123489 A123490
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KEYWORD
| nonn
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AUTHOR
| Alexander Adamchuk (alex(AT)kolmogorov.com), Sep 30 2006, Oct 02 2006
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