

A215444


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


3




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 * A006593 A115724 A039782
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



