A173828 Primes p such that p-+(floor(Sqrt(p)))^2 are primes.
7, 43, 47, 67, 149, 163, 167, 337, 353, 487, 587, 617, 787, 911, 947, 1367, 1777, 1783, 2333, 2347, 2503, 2927, 2953, 2963, 3023, 3607, 3613, 3637, 3643, 3697, 3709, 3847, 4363, 4397, 4423, 4463, 4483, 4903, 5273, 6113, 6143, 6197, 7103, 7187, 7193, 8117
Offset: 1
Keywords
Links
- Harvey P. Dale, Table of n, a(n) for n = 1..1000
Programs
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Mathematica
f1[n_]:=n-(Floor[Sqrt[n]])^2;f2[n_]:=n+(Floor[Sqrt[n]])^2;lst={};Do[p=Prime[n];If[PrimeQ[f1[p]]&&PrimeQ[f2[p]],AppendTo[lst,p]],{n,8!}];lst fQ[n_]:=Module[{c=Floor[Sqrt[n]]^2},AllTrue[n+{c,-c},PrimeQ]]; Select[ Prime[ Range[1200]],fQ] (* Harvey P. Dale, Dec 15 2021 *)