OFFSET
1,1
FORMULA
a(n) >> n (log n)^2. - Charles R Greathouse IV, Sep 11 2016
EXAMPLE
2 is in this sequence because 3*2^0 - 1 = 2 is prime.
5 is in this sequence because 3*2^1 - 1 = 5 is prime.
11 is in this sequence because 3*2^2 - 1 = 11 is prime.
PROG
(PARI) is(n)=isprime((n+1)>>valuation(n+1, 2)) && isprime(n) \\ Charles R Greathouse IV, Sep 11 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
Juri-Stepan Gerasimov, Sep 11 2016
STATUS
approved