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A147782
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Primes p such that 7^p - 2 is prime.
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1
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OFFSET
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1,1
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COMMENTS
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m=7 in the PARI script. 13 is the next base prime for which this condition holds. In fact, the base prime q in q^p-2 is prime must be of the form 6n+1.
This follows from the fact that if q = 6n-1, the binomial q^p = (6n-1)^p = 6h-1 for some h and q^p-2 = 6h-1-2 is divisible by 3 and thus not prime.
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LINKS
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FORMULA
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MATHEMATICA
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Select[Prime[Range[150]], PrimeQ[7^#-2]&] (* Harvey P. Dale, Feb 20 2013 *)
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PROG
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(PARI) g(n, m)=forprime(p=2, n, y=m^p-2; if(ispseudoprime(y), print1(p", ")))
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CROSSREFS
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KEYWORD
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nonn,hard,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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