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A215445 Numbers k such that 7^k + k^7 - 1 is prime. 3
1, 11, 65, 133, 679, 1571, 27517, 51631 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(9) > 10^5. - Robert Price, Feb 23 2014

LINKS

Table of n, a(n) for n=1..8.

MATHEMATICA

Select[Range[0, 5000], PrimeQ[7^# + #^7 - 1] &]

PROG

(PARI) is(n)=ispseudoprime(7^n+n^7-1) \\ Charles R Greathouse IV, Jun 06 2017

CROSSREFS

Cf. A100357, A215434-A215444, A216375.

Sequence in context: A237358 A250604 A233164 * A184055 A161459 A162288

Adjacent sequences:  A215442 A215443 A215444 * A215446 A215447 A215448

KEYWORD

nonn,hard,more

AUTHOR

Vincenzo Librandi, Sep 06 2012

EXTENSIONS

a(7)-a(8) from Robert Price, Feb 23 2014

STATUS

approved

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Last modified January 25 03:49 EST 2020. Contains 331241 sequences. (Running on oeis4.)