A215445 Numbers k such that 7^k + k^7 - 1 is prime.

1, 11, 65, 133, 679, 1571, 27517, 51631

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 A332750 A161459

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