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 A125743 #10 Mar 25 2014 12:32:36
%S A125743 5,31,53,163,509,1061,13627,20047,28411,50993,71453,272141,1353449
%N A125743 Primes p such that (3^p - 3^((p + 1)/2) + 1)/7 is prime.
%C A125743 PrimePi[ a(n) ] = {3, 11, 16, 38, 97, 178,...}.
%H A125743 Henri & Renaud Lifchitz, <a href="http://www.primenumbers.net/prptop/searchform.php?form=%283%5Ex-3%5Ey%2B1%29%2F7&action=Search">PRP Records</a>.
%t A125743 Do[p=Prime[n];f=(3^p-3^((p+1)/2)+1)/7;If[PrimeQ[f],Print[{n,p}]],{n,1,178}]
%Y A125743 Cf. A125744 = Primes p such that (3^p + 3^((p + 1)/2) + 1)/7 is prime. Cf. A125738 = Primes p such that 3^p - 3^((p + 1)/2) + 1 is prime. Cf. A125739 = Primes p such that 3^p + 3^((p + 1)/2) + 1 is prime. Cf. A007670, A007671, A124165, A125742.
%K A125743 hard,more,nonn
%O A125743 1,1
%A A125743 _Alexander Adamchuk_, Dec 04 2006
%E A125743 a(6)-a(11) from Lelio R Paula (lelio(AT)sknet.com.br), May 08 2008
%E A125743 a(12) from _Serge Batalov_, Mar 07 2014
%E A125743 a(13) from _Serge Batalov_, Mar 25 2014