A215444 Numbers k such that 7^k + k^7 + 1 is prime.

0, 3, 5, 15, 375, 98003

Offset

1,2

Comments

a(6) > 8000. - Joerg Arndt, Sep 29 2012

a(7) > 2*10^5. - Robert Price, Jun 15 2014

Links

Table of n, a(n) for n=1..6.

Mathematica

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

Prog

(Magma) [n: n in [0..400] | IsPrime(7^n + n^7 + 1)]
(PARI) is(n)=ispseudoprime(7^n+n^7+1) \\ Charles R Greathouse IV, Jun 06 2017

Crossrefs

Cf. A100357, A215441, A216423, A215442, A243934.

Sequence in context: A292339 A175138 A248795 * A325257 A006593 A115724

Adjacent sequences: A215441 A215442 A215443 * A215445 A215446 A215447

Keyword

nonn,hard,more

Author

Vincenzo Librandi, Sep 06 2012

Extensions

a(6) from Robert Price, May 24 2014

Status

approved