|
|
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 Mersenne-Chen prime.
Conjecture: 2^127 - 1 is the largest Mersenne-Chen prime.
|
|
LINKS
|
|
|
EXAMPLE
|
a(5)=13 because 2^13 - 1 = 8191 is prime and 2^13 + 1 = 3*2731 is semiprime.
|
|
MATHEMATICA
|
Select[Prime[Range[40]], PrimeQ[2^#-1]&&PrimeOmega[2^#+1]<3&] (* James C. McMahon, Mar 30 2024 *)
|
|
CROSSREFS
|
|
|
KEYWORD
|
hard,more,nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|