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A175172 Primes p such that 3*2^p+1 is also prime. 2

%I

%S 2,5,41,353

%N Primes p such that 3*2^p+1 is also prime.

%F A000040 INTERSECT A002253. - _R. J. Mathar_, Jan 04 2011

%e For p=2, 3*2^2+1=13; p=5. 3*2^5+1=97; p=41, 3*2^41+1=6597069766657.

%p select(p->isprime(p) and isprime(3*2^p+1),[$0..5000]); # _Muniru A Asiru_, Dec 19 2018

%t Select[Prime[Range[1000]], PrimeQ[3 2^# + 1] &] (* _Vincenzo Librandi_, Dec 19 2018 *)

%o (MAGMA) [p: p in PrimesUpTo(4000) | IsPrime(3*2^p+1)]

%Y Cf. A000040, A002253.

%K nonn,more

%O 1,1

%A _Vincenzo Librandi_, Mar 09 2010

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Last modified April 19 06:10 EDT 2021. Contains 343105 sequences. (Running on oeis4.)