1,1

If p is a prime then p is in the sequence iff 2^p-1 is a composite number.

V. Shevelev, Overpsudoprimes, Mersenne Numbers and Wieferich Primes, http://arxiv.org/abs/0806.3412

Cf. A141232, A137576, A005420, A049479.

Sequence in context: A138838 A139337 A040110 this_sequence A048136 A166713 A095779

Adjacent sequences: A140449 A140450 A140451 this_sequence A140453 A140454 A140455

nonn

Vladimir Shevelev (shevelev(AT)bgu.ac.il), Jun 26 2008