A266517 Sophie Germain primes p such that (2^(p+7)*5^(p+5)-204979)/9 is also prime.

5, 11, 239, 4073

Offset

1,1

Comments

Intersection of A005384 and A266421.

a(n) mod 19, a(n) mod 29, a(n) mod 37, and a(n) mod 59 are also primes.

a(5) > 70000 (if it exists).

Links

Table of n, a(n) for n=1..4.

Mathematica

Select[ Prime[ Range[600]], PrimeQ[2# + 1] && PrimeQ[(2^(#+7) * 5^(#+5) - 204979) / 9] &]

Prog

(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

Crossrefs

Cf. A005384, A266421

Sequence in context: A159009 A230841 A139187 * A228054 A283354 A156330

Adjacent sequences: A266514 A266515 A266516 * A266518 A266519 A266520

Keyword

nonn,hard,more

Author

Mikk Heidemaa, Dec 30 2015

Status

approved