A137771 Prime numbers p such that p +- ((p-1)/8) are primes.

241, 433, 1153, 2593, 3121, 5521, 6673, 7393, 8353, 8641, 10513, 13681, 19441, 21121, 22273, 32401, 34273, 43441, 48193, 49201, 54721, 62401, 68881, 69313, 71473, 74161, 77761, 86161, 87121, 104113, 105601, 114913, 116833, 119953

Offset

1,1

Links

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

Example

241+-(240/8) = primes;
433+-(432/8) = primes.

Mathematica

w=8; 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[15000]], PrimeQ[ # + (# - 1)/8] && PrimeQ[ # - (# - 1)/8] &] (* Stefan Steinerberger, May 02 2008 *)
Select[Prime[Range[15000]], AllTrue[#+{(#-1)/8, -(#-1)/8}, PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Nov 04 2017 *)

Prog

(Magma) [p: p in PrimesInInterval(5, 120000)| IsPrime((9*p-1) div 8 ) and IsPrime((7*p+1) div 8)]; // Vincenzo Librandi, Jun 15 2013

Crossrefs

Sequence in context: A140629 A325088 A321582 * A342681 A108831 A068706

Adjacent sequences: A137768 A137769 A137770 * A137772 A137773 A137774

Keyword

nonn,easy

Author

Vladimir Joseph Stephan Orlovsky, Apr 27 2008

Extensions

More terms from Stefan Steinerberger, May 02 2008

Status

approved