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A137714 Prime numbers p such that p +- ((p-1)/5) are primes. 2
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 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
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
KEYWORD
nonn,easy
AUTHOR
EXTENSIONS
More terms from Vincenzo Librandi, Jun 15 2013
STATUS
approved

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Last modified May 28 21:13 EDT 2024. Contains 372920 sequences. (Running on oeis4.)