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A113916 Numbers n such that (p^n-1)/(p-1) is prime where p is the n-th prime. 0
3, 7, 19, 31, 307, 421 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Note that n must itself be a prime.
LINKS
MATHEMATICA
Do[ p = Prime[n]; If[PrimeQ[(p^n - 1)/(p - 1)], Print[n]], {n, 1800}] (* Robert G. Wilson v *)
CROSSREFS
Sequence in context: A102271 A145039 A112633 * A227502 A268065 A049490
KEYWORD
nonn
AUTHOR
Joao da Silva (zxawyh66(AT)yahoo.com), Jan 30 2006
STATUS
approved

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Last modified April 15 00:51 EDT 2024. Contains 371667 sequences. (Running on oeis4.)