A143794 Primes p, with index k, such that p-k and p+k are both prime.

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

Offset

1,1

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Example

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.

Mathematica

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 *)

Prog

(PARI) n=0; forprime(p=2, 1e5, if(isprime(p-n++)&&isprime(p+n), print1(p", "))) \\ Charles R Greathouse IV, Nov 04 2011

Crossrefs

Cf. A064403 (corresponding prime indices).

Sequence in context: A253210 A183180 A133664 * A334794 A325029 A159198

Adjacent sequences: A143791 A143792 A143793 * A143795 A143796 A143797

Keyword

nonn

Author

Vladimir Joseph Stephan Orlovsky, Sep 01 2008

Extensions

Definition edited by Harvey P. Dale, Nov 04 2011

Status

approved