|
|
A054723
|
|
Prime exponents of composite Mersenne numbers.
|
|
41
|
|
|
11, 23, 29, 37, 41, 43, 47, 53, 59, 67, 71, 73, 79, 83, 97, 101, 103, 109, 113, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 293, 307, 311, 313, 317, 331
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
COMMENTS
|
Primes p such that 2^p-1 is composite.
No proof is known that this sequence is infinite!
Assuming a conjecture of Dickson, we can prove that this sequence is infinite. See Ribenboim. - T. D. Noe, Jul 30 2012
|
|
REFERENCES
|
Paulo Ribenboim, The New Book of Prime Number Records, Springer, 1996, p. 378.
|
|
LINKS
|
|
|
EXAMPLE
|
p=29 is included because 29 is prime, but 2^29-1 is *not* prime.
|
|
MATHEMATICA
|
Select[Prime[Range[70]], ! PrimeQ[2^# - 1] &] (* Harvey P. Dale, Feb 03 2011 *)
Module[{nn=15, mp}, mp=MersennePrimeExponent[Range[nn]]; Complement[ Prime[ Range[ PrimePi[Last[mp]]]], mp]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Apr 10 2019 *)
|
|
PROG
|
(Magma) [p: p in PrimesUpTo(350) | not IsPrime(2^p-1)]; // Bruno Berselli, Oct 11 2012
(PARI) forprime(p=2, 1e3, if(!isprime(2^p-1), print1(p, ", "))) \\ Felix Fröhlich, Aug 10 2014
|
|
CROSSREFS
|
|
|
KEYWORD
|
easy,nonn
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|