A265485 Numbers n such that 49^n - 7^n - 1 is prime.

1, 2, 12, 14, 110, 2574, 10964, 24257, 44364

Offset

1,2

Comments

For n = 1, 2, 12, 14 the corresponding primes are 41, 2351, 191581231366725127199, 459986536544061737903951.

a(10) > 10^5. - Robert Price, Dec 25 2019

Links

Table of n, a(n) for n=1..9.

Example

2 is in the sequence because 49^2 - 7^2 - 1 = 2351 is prime.

Mathematica

Select[Range[2000], PrimeQ[49^# - 7^# - 1] &]

Prog

(Magma) [n: n in [0..1000] | IsPrime(49^n - 7^n - 1)];
(PARI) for(n=1, 1e3, if(ispseudoprime(49^n - 7^n - 1), print1(n, ", "))) \\ Altug Alkan, Dec 12 2015

Crossrefs

Cf. similar sequences listed in A265481.

Sequence in context: A260899 A108969 A269130 * A166745 A352504 A262094

Adjacent sequences: A265482 A265483 A265484 * A265486 A265487 A265488

Keyword

nonn,more

Author

Vincenzo Librandi, Dec 12 2015

Extensions

a(6) from Ray Chandler, Sep 25 2019

a(7)-a(9) from Robert Price, Dec 25 2019

Status

approved