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A266517
Sophie Germain primes p such that (2^(p+7)*5^(p+5)-204979)/9 is also prime.
0
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).
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
KEYWORD
nonn,hard,more
AUTHOR
Mikk Heidemaa, Dec 30 2015
STATUS
approved