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 A087506 #5 May 06 2013 10:09:12
%S A087506 5,13,71,127,163,197,227,307,317,409,523,587,593,761,857,947,1151,
%T A087506 1321,1373,1783,1861,1973,2039,2273,2417,2543,3049,3083,3457,3463,
%U A087506 3697,3739,4093,4243,4253,4463,4483,4519,4583,4657,4723,4751,5171,5179,5519,5591
%N A087506 Primes in A087461.
%C A087506 Primes of the form (prime(k)+prime(2k))/2.
%t A087506 Select[Table[(Prime[n]+Prime[2n])/2,{n,500}],PrimeQ] (* _Harvey P. Dale_, May 06 2013 *)
%Y A087506 Cf. A087461.
%K A087506 nonn
%O A087506 1,1
%A A087506 _Ray Chandler_, Sep 10 2003