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 A073123 #15 Jun 30 2021 10:36:54
%S A073123 4,6,12,18,36,42,60,70,88,112,130,162,180,192,222,250,280,292,336,358,
%T A073123 372,408,432,462,520,556,568,592,600,618,718,742,786,808,862,880,928,
%U A073123 970,996,1032,1068,1090,1162,1180,1212,1222,1300,1422,1438,1450,1480
%N A073123 a(n) is the largest number such that pi(a(n)) = prime(n).
%C A073123 Primes with prime subscripts correspond to least numbers m, such that pi(m) = prime(n).
%H A073123 Robert Israel, <a href="/A073123/b073123.txt">Table of n, a(n) for n = 1..10000</a>
%F A073123 a(n) = Max{x: A000720(x)=A000040(n)}.
%F A073123 a(n) = A000040(A000040(n)+1) - 1.
%e A073123 n=25: prime(25)=97; for 12 terms X = {509, 510, 511, 512, 513, 514, 515, 516, 517, 518, 519, 520}, pi(X)=97. Largest is a(25)=520, smallest is A006450(25), number of terms = A073124(25).
%p A073123 seq(ithprime(ithprime(n)+1)-1, n=1..100); # _Robert Israel_, May 14 2018
%Y A073123 Cf. A000720, A000040, A006450, A073124.
%Y A073123 Equals A072677(n) - 1.
%K A073123 nonn
%O A073123 1,1
%A A073123 _Labos Elemer_, Jul 16 2002
%E A073123 Edited by _Robert Israel_, May 14 2018