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A125957
Numbers n such that (2^n + 11^n)/13 is prime.
5
3, 5, 17, 67, 83, 101, 1373, 6101, 12119, 61781
OFFSET
1,1
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
MATHEMATICA
Do[p=Prime[n]; f=(2^p+11^p)/13; If[PrimeQ[f], Print[{p, f}]], {n, 1, 100}]
PROG
(PARI) is(n)=ispseudoprime((2^n+11^n)/13) \\ Charles R Greathouse IV, Feb 20 2017
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.
Sequence in context: A265425 A256438 A251737 * A374150 A259908 A137460
KEYWORD
hard,more,nonn
AUTHOR
Alexander Adamchuk, Feb 06 2007
EXTENSIONS
2 more terms from Ryan Propper, Feb 09 2008
a(9)-a(10) from Robert Price, Feb 26 2013
STATUS
approved