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A265485
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Numbers n such that 49^n - 7^n - 1 is prime.
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1
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OFFSET
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1,2
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COMMENTS
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For n = 1, 2, 12, 14 the corresponding primes are 41, 2351, 191581231366725127199, 459986536544061737903951.
a(10) > 10^5. - Robert Price, Dec 25 2019
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LINKS
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Table of n, a(n) for n=1..9.
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EXAMPLE
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2 is in the sequence because 49^2 - 7^2 - 1 = 2351 is prime.
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MATHEMATICA
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Select[Range[2000], PrimeQ[49^# - 7^# - 1] &]
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PROG
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(MAGMA) [n: n in [0..1000] | IsPrime(49^n - 7^n - 1)];
(PARI) for(n=1, 1e3, if(ispseudoprime(49^n - 7^n - 1), print1(n, ", "))) \\ Altug Alkan, Dec 12 2015
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CROSSREFS
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Cf. similar sequences listed in A265481.
Sequence in context: A260899 A108969 A269130 * A166745 A352504 A262094
Adjacent sequences: A265482 A265483 A265484 * A265486 A265487 A265488
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KEYWORD
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nonn,more
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AUTHOR
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Vincenzo Librandi, Dec 12 2015
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EXTENSIONS
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a(6) from Ray Chandler, Sep 25 2019
a(7)-a(9) from Robert Price, Dec 25 2019
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STATUS
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approved
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