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A109799
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Primes p such that 2^p - 1 is a Chen prime.
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1
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OFFSET
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1,1
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COMMENTS
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For p in this sequence, 2^p - 1 is called a Mersenne-Chen prime.
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 given by A107360. - Max Alekseyev, Oct 28 2008, Jan 28 2010
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LINKS
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Table of n, a(n) for n=1..10.
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EXAMPLE
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a(5)=13 because 2^13 - 1 = 8191 is prime and 2^13 + 1 = 3*2731 is semiprime.
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CROSSREFS
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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
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KEYWORD
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hard,more,nonn
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AUTHOR
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Jason Earls, Aug 15 2005
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STATUS
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approved
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