

A109799


Primes p such that 2^p  1 is a Chen prime.


1




OFFSET

1,1


COMMENTS

For p in this sequence, 2^p  1 is called a MersenneChen prime.
Conjecture: 2^127  1 is the largest MersenneChen prime.
Except for the initial term 2, this sequence is the intersection of A000043 and A000978 given by A107360.  Max Alekseyev, Oct 28 2008, Jan 28 2010


LINKS

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


EXAMPLE

a(5)=13 because 2^13  1 = 8191 is prime and 2^13 + 1 = 3*2731 is semiprime.


CROSSREFS

Cf. A000043, A109611.
First 10 members equals A152961.  Omar E. Pol, Dec 20 2008
Sequence in context: A120857 A233516 A000043 * A152961 A109461 A138539
Adjacent sequences: A109796 A109797 A109798 * A109800 A109801 A109802


KEYWORD

hard,more,nonn


AUTHOR

Jason Earls, Aug 15 2005


STATUS

approved



