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A125956
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Numbers k such that (2^k + 9^k)/11 is prime.
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7
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OFFSET
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1,1
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COMMENTS
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All terms are primes. Note that first 3 terms (3, 7, 127} are primes of the form 2^q - 1, where q = {2, 3, 7) is prime too. Corresponding primes of the form (2^n + 9^n)/11 are {67, 434827, ...}.
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LINKS
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MATHEMATICA
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Do[p=Prime[n]; f=(2^p+9^p)/11; If[PrimeQ[f], Print[{p, f}]], {n, 1, 100}]
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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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