A137770 Prime numbers p such that p +- ((p-1)/7) are primes.

211, 673, 883, 1093, 1303, 2731, 7561, 8443, 10711, 13063, 14323, 15373, 16843, 18523, 24571, 30703, 31081, 31963, 36541, 36583, 40111, 41161, 42043, 43051, 44563, 44773, 55441, 63421, 64891, 65563, 67411, 68041, 70393, 71233, 74551, 75391, 79843

Offset

1,1

Links

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

Example

211+-30 = primes;
673+-(672/7) = primes.

Mathematica

w=7; 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[80000]], PrimeQ[# + (# - 1) / 7] && PrimeQ[# - (# - 1) / 7] &] (* Vincenzo Librandi, Jun 15 2013 *)

Prog

(Magma) [p: p in PrimesInInterval(5, 80000)| IsPrime((8*p-1) div 7 ) and IsPrime((6*p+1) div 7)]; // Vincenzo Librandi, Jun 15 2013

Crossrefs

Sequence in context: A299110 A236722 A236878 * A142761 A308798 A342508

Adjacent sequences: A137767 A137768 A137769 * A137771 A137772 A137773

Keyword

nonn,easy

Author

Vladimir Joseph Stephan Orlovsky, Apr 27 2008

Status

approved