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A125955
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Numbers k such that (2^k + 7^k)/9 is prime.
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1
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5, 23, 73, 101, 401, 419, 457, 811, 1163, 1511, 8011
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OFFSET
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1,1
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COMMENTS
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All terms are primes. Corresponding primes of the form (2^k + 7^k)/9 are {1871, 3040971926676589439, 5469081705798319217773539465593130845206220817280793349743311, ...}.
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LINKS
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MATHEMATICA
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Do[p=Prime[n]; f=(2^p+7^p)/9; If[PrimeQ[f], Print[{p, f}]], {n, 1, 1000}]
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PROG
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CROSSREFS
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Cf. A000978 = numbers n such that (2^n + 1)/3 is prime. Cf. A057469 = numbers n such that (2^n + 3^n)/5 is prime. Cf. A082387 = numbers n such that (2^n + 5^n)/7 is prime.
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KEYWORD
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hard,more,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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