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A278053
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Primes p such that sigma(2^(p+1)) is prime.
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1
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3, 5, 11, 17, 29, 59, 1277, 4421, 110501, 132047, 20996009, 24036581
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OFFSET
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1,1
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COMMENTS
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Corresponding values of primes q are in A278054.
See A000043 (Mersenne exponents) - numbers n such that sigma(2^(n-1)) is a prime.
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LINKS
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EXAMPLE
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Prime 11 is in the sequence because sigma(2^(11+1)) = sigma(4096) = 8191 (prime).
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MATHEMATICA
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PROG
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(Magma) [n: n in [1..10000] | IsPrime(n) and IsPrime(SumOfDivisors(2^(n+1)))]
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CROSSREFS
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KEYWORD
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hard,nonn,more
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AUTHOR
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STATUS
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approved
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