|
Search: id:A109799
|
|
|
| A109799 |
|
Primes p such that 2^p - 1 is a Chen prime. 2^p - 1 is then called a Mersenne Chen prime. |
|
+0
2
|
| |
|
|
OFFSET
|
1,1
|
|
|
COMMENT
|
Conjecture: 2^127 - 1 is the largest Mersenne Chen prime.
Except for the initial term 2, this sequence is the intersection of A000043 and A000978. [From Max Alekseyev (maxale(AT)gmail.com), Oct 28 2008]
First 10 members equals A152961. [From Omar E. Pol (info(AT)polprimos.com), Dec 20 2008]
|
|
EXAMPLE
|
a(5)=13 because 2^13 - 1 = 8191 is prime and 2^13 + 1 = 3*2731 is semiprime.
|
|
CROSSREFS
|
Cf. A000043, A109611.
Cf. A152961. [From Omar E. Pol (info(AT)polprimos.com), Dec 20 2008]
Sequence in context: A123856 A120857 A000043 this_sequence A152961 A109461 A138539
Adjacent sequences: A109796 A109797 A109798 this_sequence A109800 A109801 A109802
|
|
KEYWORD
|
hard,more,nonn
|
|
AUTHOR
|
Jason Earls (zevi_35711(AT)yahoo.com), Aug 15 2005
|
|
|
Search completed in 0.002 seconds
|
