1,1

Table of n, a(n) for n=1..55.

a(n) >> n (log n)^2. - Charles R Greathouse IV, Sep 11 2016

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.

(PARI) is(n)=isprime((n+1)>>valuation(n+1, 2)) && isprime(n) \\ Charles R Greathouse IV, Sep 11 2016

Essentially the same as A192869 and A206581.

Cf. A038550, A058500.

Sequence in context: A191048 A105961 A045361 * A086081 A113305 A095078

Adjacent sequences: A276657 A276658 A276659 * A276661 A276662 A276663

nonn

Juri-Stepan Gerasimov, Sep 11 2016

approved