A137714 Prime numbers p such that p +- ((p-1)/5) are primes.

1291, 5701, 6961, 7351, 7591, 8101, 8191, 10651, 10861, 12211, 12511, 15361, 15901, 16111, 17341, 18061, 19051, 19861, 19891, 23761, 24091, 24691, 25111, 26161, 29611, 34261, 34351, 35491, 35911, 37201, 38791, 39841, 47491, 47911, 49261

Offset

1,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Example

1291+1290/5 = 1549 and 1291-1290/5 = 1033, which are primes;
5701+5700/5 = 6841 and 5701-5700/5 = 4561, which are primes.

Mathematica

w=5; s=""; For[i=1, i<10^3*2, p=Prime[i]; If[PrimeQ[p-((p-1)/w)]&&PrimeQ[p+((p-1)/w)], (*Print[p, ":", p-((p-1)/w), ", ", p+((p-1)/w)]; *)s=s<>ToString[p]<>", "]; i++ ]; Print[s]
Select[Prime[Range[50000]], PrimeQ[# + (# - 1) / 5] && PrimeQ[# - (# - 1) / 5] &] (* Vincenzo Librandi, Jun 15 2013 *)

Prog

(Magma) [p: p in PrimesInInterval(5, 50000)| IsPrime((6*p-1) div 5 ) and IsPrime((4*p+1) div 5)]; // Vincenzo Librandi, Jun 15 2013

Crossrefs

Sequence in context: A264243 A020401 A106816 * A256677 A139027 A043392

Adjacent sequences: A137711 A137712 A137713 * A137715 A137716 A137717

Keyword

nonn,easy

Author

Vladimir Joseph Stephan Orlovsky, Apr 27 2008

Extensions

More terms from Vincenzo Librandi, Jun 15 2013

Status

approved