|
%I #27 Sep 08 2022 08:46:13
%S 2,3,5,7,23,37,47,263,317,3229,3253
%N Primes p such that 2^p + 9 is also prime.
%C a(12) > 100000. - _Dana Jacobsen_, Oct 03 2015
%e 5 is in sequence because 2^5 + 9 = 41 is prime.
%t Select[Prime[Range[1000]], PrimeQ[2^# + 9] &]
%o (Magma) [p: p in PrimesUpTo(1000) | IsPrime(2^p+9)];
%o (PARI) for(n=1, 1e3, if(isprime((2^prime(n))+9), print1(prime(n)", "))) \\ _Altug Alkan_, Sep 18 2015
%o (Perl) use ntheory ":all"; use Math::GMP qw/:constant/; forprimes { say if is_prime(2**$_+9) } 10000; # _Dana Jacobsen_, Oct 03 2015
%Y Subsequence of primes of A057196.
%Y Cf. primes p such that 2^p+k is a prime: A057736 (k=3), A175173 (k=5), this sequence (k=9), A155780 (k=11), A175234 (k=15), A262099 (k=17), A175235 (k=21), A175236 (k=23), A262934 (k=27), A262100 (k=29), A262201 (k=33), A262962 (k=35).
%K nonn,more
%O 1,1
%A _Vincenzo Librandi_, Sep 18 2015
|
