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A263686
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Smallest prime factor of double Mersenne numbers.
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3
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OFFSET
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1,1
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COMMENTS
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A double Mersenne number is a Mersenne number of the form 2^(2^p - 1) - 1, where p is a Mersenne exponent (A000043).
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LINKS
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Double Mersennes Prime Search, History
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PROG
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(PARI) forprime(p=2, , q=2^p-1; !ispseudoprime(q) && next(); if(ispseudoprime(2^q-1), print1(2^q-1, ", "); next()); forstep(r=2*q+1, +oo, 2*q, !ispseudoprime(r) && next(); if(Mod(2, r)^q-1 == 0, print1(r, ", "); next(2)))) \\ Jeppe Stig Nielsen, Aug 28 2019
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CROSSREFS
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KEYWORD
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nonn,hard,more
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AUTHOR
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STATUS
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approved
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