This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A164621 #10 Jun 04 2020 20:23:45
%S A164621 7,31,79,211,271,751,787,1231,1447,1459,2347,2551,3727,5119,6427,6691,
%T A164621 8467,8707,9007,10099,10531,10567,10831,11959,18691,21487,22039,22567,
%U A164621 23059,23167,23371,24379,24499,25171,26371,27967,28579,28591,29287
%N A164621 Primes p such that p*floor(p/2)-2 and p*floor(p/2)+2 are also prime numbers.
%H A164621 Vincenzo Librandi, <a href="/A164621/b164621.txt">Table of n, a(n) for n = 1..1000</a>
%e A164621 7*3-2=13, 7*3+2=17,..
%t A164621 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
%t A164621 Select[Prime[Range[3200]],AllTrue[# Floor[#/2]+{2,-2},PrimeQ]&] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Jun 04 2020 *)
%Y A164621 Cf. A068229, A158708, A164620
%K A164621 nonn
%O A164621 1,1
%A A164621 _Vladimir Joseph Stephan Orlovsky_, Aug 17 2009