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A267943
Numbers n such that 2^n - 3 and 3*2^n - 1 are both prime.
0
OFFSET
1,1
COMMENTS
The intersection of A002235 and A050414 is not empty (3 does not belong to A267985).
FORMULA
A002235 INTERSECT A050414.
EXAMPLE
a(3) = 6 because 2^6 - 3 = 61 and 3*2^6 - 1 = 191 are both prime.
PROG
(Magma) [n: n in [2..94] | IsPrime(2^n-3) and IsPrime(3*2^n-1)];
(PARI) isok(n) = isprime(2^n-3) && isprime(3*2^n-1);
CROSSREFS
KEYWORD
nonn,hard,more
AUTHOR
STATUS
approved