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A143794
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Primes p, with index k, such that p-k and p+k are both prime.
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4
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7, 13, 61, 181, 317, 827, 1831, 2657, 2801, 3181, 3739, 4093, 4561, 5011, 5443, 5531, 5653, 6359, 6659, 9029, 10729, 11383, 13109, 13907, 14489, 15217, 15859, 16603, 17581, 20393, 21499, 23537, 25037, 25169, 26153, 26959, 27077, 27803, 27851
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OFFSET
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1,1
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LINKS
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EXAMPLE
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7 = prime(4) and both 7 - 4 = 3 and 7 + 4 = 11 are prime;
13 = prime(6) and both 13 - 6 = 7 and 13 + 6 = 19 are prime;
61 = prime(18) and both 61 - 18 = 43 and 61 + 18 = 79 are prime.
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MATHEMATICA
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lst={}; Do[p=Prime[n]; If[PrimeQ[p-n]&&PrimeQ[p+n], AppendTo[lst, p]], {n, 8!}]; lst
Transpose[Select[Table[{n, Prime[n]}, {n, 3100}], And@@PrimeQ[{Last[#]- First[#], Total[#]}]&]][[2]] (* Harvey P. Dale, Nov 04 2011 *)
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PROG
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(PARI) n=0; forprime(p=2, 1e5, if(isprime(p-n++)&&isprime(p+n), print1(p", "))) \\ Charles R Greathouse IV, Nov 04 2011
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CROSSREFS
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Cf. A064403 (corresponding prime indices).
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KEYWORD
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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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