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A103901
Mersenne primes p such that M(p) = 2^p - 1 is also a (Mersenne) prime.
3
3, 7, 31, 127
OFFSET
1,1
COMMENTS
Same as exponents of double Mersenne primes. Only four terms are known.
REFERENCES
R. K. Guy, Unsolved Problems in Number Theory, 3rd ed., Springer-Verlag, NY, 2004, Sec. A3.
G. H. Hardy and E. M. Wright, An Introduction to the Theory of Numbers, 3rd ed., Oxford Univ. Press, 1954, p. 16.
P. Ribenboim, The New Book of Prime Number Records, Springer-Verlag, NY, 1996, Chap. 2, Sec. VII.
LINKS
EXAMPLE
2^2 - 1 = 3 and 2^3 - 1 = 7 are Mersenne primes, so 3 is a member.
CROSSREFS
KEYWORD
nonn,more,hard
AUTHOR
Jonathan Sondow, Feb 20 2005
STATUS
approved