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A164621
Primes p such that p*floor(p/2)-2 and p*floor(p/2)+2 are also prime numbers.
3
7, 31, 79, 211, 271, 751, 787, 1231, 1447, 1459, 2347, 2551, 3727, 5119, 6427, 6691, 8467, 8707, 9007, 10099, 10531, 10567, 10831, 11959, 18691, 21487, 22039, 22567, 23059, 23167, 23371, 24379, 24499, 25171, 26371, 27967, 28579, 28591, 29287
OFFSET
1,1
LINKS
EXAMPLE
7*3-2=13, 7*3+2=17,..
MATHEMATICA
lst={}; Do[p=Prime[n]; If[PrimeQ[p*Floor[p/2]-2]&&PrimeQ[p*Floor[p/2]+2], AppendTo[lst, p]], {n, 2*7!}]; lst
Select[Prime[Range[3200]], AllTrue[# Floor[#/2]+{2, -2}, PrimeQ]&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jun 04 2020 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved