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 A237658 #21 Apr 28 2018 03:40:32
%S A237658 6,17,33,34,41,59,60,69,109,110,111,127,157,161,246,287,335,353,367,
%T A237658 368,404,600,709,711,713,718,740,779,804,1153,1162,1175,1437,1472,
%U A237658 1500,1526,1527,1679,1729,1742,1787,1826,2028,2082,2104,2223,2422,2616,2649,2651
%N A237658 Positive integers m with pi(m) and pi(m^2) both prime, where pi(.) is given by A000720.
%C A237658 The conjecture in A237657 implies that this sequence has infinitely many terms.
%C A237658 For primes in this sequence, see A237659.
%H A237658 Chai Wah Wu, <a href="/A237658/b237658.txt">Table of n, a(n) for n = 1..10001</a> (n = 1..3000 from Zhi-Wei Sun)
%e A237658 a(1) = 6 since pi(6) = 3 and pi(6^2) = 11 are both prime, but none of pi(1) = 0, pi(2) = 1, pi(3^2) = 4, pi(4^2) = 6 and pi(5^2) = 9 is prime.
%t A237658 p[m_]:=PrimeQ[PrimePi[m]]&&PrimeQ[PrimePi[m^2]]
%t A237658 n=0;Do[If[p[m],n=n+1;Print[n," ",m]],{m,1,1000}]
%o A237658 (PARI) isok(n) = isprime(primepi(n)) && isprime(primepi(n^2)); \\ _Michel Marcus_, Apr 28 2018
%Y A237658 Cf. A000040, A000290, A038107, A237595, A237656, A237657, A237659.
%K A237658 nonn
%O A237658 1,1
%A A237658 _Zhi-Wei Sun_, Feb 10 2014