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A174267 Primes p such that 5^p-4 is also prime. 0

%I

%S 5,7,47

%N Primes p such that 5^p-4 is also prime.

%F A000040 INTERSECT A059613. - _R. J. Mathar_, Apr 15 2010

%e For p=5, 5^5-4=3121; p=7, 5^7-4=78121; p=47, 5^47-4= 710542735760100185871124267578121

%o (MAGMA) [ p: p in PrimesUpTo(3500)| IsPrime(5^p-4)]

%o (PARI) is(n)=isprime(n) && isprime(5^n-4) \\ _Charles R Greathouse IV_, Sep 06 2016

%K nonn,more,bref

%O 1,1

%A _Vincenzo Librandi_, Mar 14 2010

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Last modified July 2 08:02 EDT 2020. Contains 335398 sequences. (Running on oeis4.)