%I #19 Sep 08 2022 08:46:15
%S 5,11,239,4073
%N Sophie Germain primes p such that (2^(p+7)*5^(p+5)-204979)/9 is also prime.
%C Intersection of A005384 and A266421.
%C a(n) mod 19, a(n) mod 29, a(n) mod 37, and a(n) mod 59 are also primes.
%C a(5) > 70000 (if it exists).
%t Select[ Prime[ Range[600]], PrimeQ[2# + 1] && PrimeQ[(2^(#+7) * 5^(#+5) - 204979) / 9] &]
%o (Magma) [p: p in PrimesUpTo(500) | IsPrime(2*p+1) and IsPrime((2^(p+7)*5^(p+5)-204979) div 9)]; // _Vincenzo Librandi_, Jan 07 2016
%Y Cf. A005384, A266421
%K nonn,hard,more
%O 1,1
%A _Mikk Heidemaa_, Dec 30 2015