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A158795
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Primes of the form 2*7^k - 1.
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5
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13, 97, 4801, 33613, 1356446145697, 383162462761132828801, 6439811511626359453675213, 5303461691719306943558046763201, 1498096661930372466988988205389128987297, 81072431194288773664131732218033347601750444502024167492384908896001
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OFFSET
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1,1
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COMMENTS
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All terms are of the form 12*k + 1. - Altug Alkan, Sep 22 2018
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LINKS
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EXAMPLE
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2*7^1 - 1 = 13, 2*7^2 - 1 = 97, and 2*7^4 - 1 = 4801 are primes, but 2*7^3 - 1 = 685 is not.
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MATHEMATICA
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PROG
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(Magma) [a: n in [0..100] | IsPrime(a) where a is 2*7^n-1 ]; // Vincenzo Librandi, Jul 26 2012
(PARI) for(k=1, 1e3, if(ispseudoprime(p=2*7^k-1), print1(p, ", "))); \\ Altug Alkan, Sep 22 2018
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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