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A215444 Numbers k such that 7^k + k^7 + 1 is prime. 3
0, 3, 5, 15, 375, 98003 (list; graph; refs; listen; history; text; internal format)
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

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Last modified December 12 13:52 EST 2018. Contains 318063 sequences. (Running on oeis4.)