1,1

These are the primes in A002235. [From R. J. Mathar, May 02 2010]

Table of n, a(n) for n=1..10.

For p=2, 3*2^2-1=11; p=3, 3*2^3-1=23; p=7, 3*2^7-1=383

(Magma) [p: p in PrimesUpTo(7000) | IsPrime(3*2^p-1) ]

Sequence in context: A072534 A056292 A106125 * A073609 A267091 A053781

Adjacent sequences: A175168 A175169 A175170 * A175172 A175173 A175174

nonn

Vincenzo Librandi, Mar 09 2010

3 more terms from R. J. Mathar, May 02 2010

approved