A125957 Numbers n such that (2^n + 11^n)/13 is prime.

3, 5, 17, 67, 83, 101, 1373, 6101, 12119, 61781

Offset: 1

Author

Alexander Adamchuk, Feb 06 2007

Keywords

• hard
• more
• nonn

Comments

All terms are primes. Corresponding primes of the form (2^n + 11^n)/13 are {103, 12391, 38880540653801911, ...}.

a(11) > 10^5. - Robert Price, Feb 26 2013

Crossrefs

Cf. A000978 = numbers n such that (2^n + 1)/3 is prime. Cf. A057469 = numbers n such that (2^n + 3^n)/5 is prime. Cf. A082387 = numbers n such that (2^n + 5^n)/7 is prime.

Programs

Mathematica

Do[p=Prime[n];f=(2^p+11^p)/13; If[PrimeQ[f], Print[{p, f}]], {n, 1, 100}]

PARI

is(n)=ispseudoprime((2^n+11^n)/13) \\ Charles R Greathouse IV, Feb 20 2017

Extensions

2 more terms from Ryan Propper, Feb 09 2008

a(9)-a(10) from Robert Price, Feb 26 2013