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A128027
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Numbers n such that (11^n - 3^n)/8 is prime.
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33
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3, 5, 19, 31, 367, 389, 431, 2179, 10667, 13103, 90397
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OFFSET
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1,1
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COMMENTS
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All terms are primes.
No other terms < 10^5.
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LINKS
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MAPLE
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MATHEMATICA
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k=8; Select[ Prime[ Range[1, 200] ], PrimeQ[ ((k+3)^# - 3^#)/k ]& ]
Do[If[PrimeQ[(11^n - 3^n)/8], Print[n]], {n, 10^4}] (* Ryan Propper, Mar 17 2007 *)
Select[Prime[Range[1200]], PrimeQ[(11^# - 3^#)/8] &] (* Vincenzo Librandi, Nov 20 2014 *)
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PROG
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(Magma) [p: p in PrimesUpTo(400) | IsPrime((11^p-3^p) div 8)]; // Vincenzo Librandi, Nov 20 2014
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CROSSREFS
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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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