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A123487 Smallest prime q such that (q^p-1)/(q-1) is prime, where p = Prime[n]; or 0 if no such prime q exists. +0
4
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; listen)
OFFSET

1,1

COMMENT

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.

CROSSREFS

Cf. A123488, A066180, A084732.

Sequence in context: A130086 A084731 A066180 this_sequence A130325 A154097 A107604

Adjacent sequences: A123484 A123485 A123486 this_sequence A123488 A123489 A123490

KEYWORD

nonn

AUTHOR

Alexander Adamchuk (alex(AT)kolmogorov.com), Sep 30 2006, Oct 02 2006

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Last modified November 25 08:46 EST 2009. Contains 167481 sequences.


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