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A117706
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Numbers n such that 6^n-n^6 is prime.
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8
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OFFSET
| 1,2
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COMMENTS
| a(9) found by Donovan Johnson
Comment from Donovan Johnson : A117705 and A117706 are both Fermat probable prime to four bases. They have also passed a Miller-Rabin primality test in five randomly chosen bases. I checked the n values up to 70000 for A117705 and n values up to 60000 for A117706. No additional primes or probable primes were found.
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EXAMPLE
| a(2)=7 because 6^7 - 7^6 = 162287 is prime
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MATHEMATICA
| Do[If[PrimeQ[(6^n-n^6)], Print[n]], {n, 1, 3000}]
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CROSSREFS
| Sequence in context: A060983 A001001 A067692 * A066673 A173230 A155036
Adjacent sequences: A117703 A117704 A117705 * A117707 A117708 A117709
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KEYWORD
| hard,more,nonn
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AUTHOR
| Mohammed Bouayoun (Mohammed.Bouayoun(AT)sanef.com), Apr 13 2006, Jan 08 2008
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