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A308079
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Pseudoprimes to base 3 that divide a Mersenne number.
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1
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10974881, 193949641, 717653129, 8762386393, 19683169273, 24802217129, 78618861353, 121271968201, 146050578391, 169905267617, 188684740591, 232153956569, 290762221753, 306091598201, 336675266287, 394233108121, 592050558553
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OFFSET
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1,1
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COMMENTS
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Odd members k of A005935 such that the multiplicative order of 2 modulo k is a prime. Odd members k of A005935 such that A002326((k-1)/2) is prime.
The known entries are proper divisors of a Mersenne number. It is not known if the Mersenne number itself can belong to this sequence.
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LINKS
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EXAMPLE
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10974881 is in the sequence because it divides 2^239 - 1 (and 239 is prime), it is not a prime, but 3^10974880 === 1 (mod 10974881).
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PROG
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(PARI) forstep(n=3, +oo, 2, Mod(3, n)^(n-1)==1&&!ispseudoprime(n)&&ispseudoprime(znorder(Mod(2, n)))&&print1(n, ", "))
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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