login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A173828
Primes p such that p-+(floor(Sqrt(p)))^2 are primes.
1
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
1,1
LINKS
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 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved