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 A070804 #12 Sep 08 2022 08:45:06
%S A070804 0,0,1,1,2,1,3,2,3,2,4,2,5,3,4,4,6,3,7,4,5,4,8,4,8,5,7,5,9,4,10,6,8,6,
%T A070804 9,5,11,7,9,6,12,5,13,8,9,8,14,6,13,8,11,9,15,7,12,9,11,9,16,6,17,10,
%U A070804 11,11,15,8,18,11,14,9,19,9,20,11,12,11,17,9,21,11,16,12,22,9,18,13,16
%N A070804 Number of primes not exceeding phi(n).
%H A070804 Vincenzo Librandi, <a href="/A070804/b070804.txt">Table of n, a(n) for n = 1..2000</a>
%F A070804 a(n) = A000720(A000010(n)) = pi(phi(n)).
%e A070804 n=50: phi[50]=20,Pi[20]=8=a(50)
%t A070804 Table[PrimePi[EulerPhi[n]], {n, 1, 256}]
%o A070804 (Magma) [#PrimesUpTo(EulerPhi(n)): n in [1..90]]; // _Vincenzo Librandi_, Mar 26 2017
%Y A070804 Cf. A007818, A000010, A000720, A070800, A070801, A070802, A070803.
%K A070804 easy,nonn
%O A070804 1,5
%A A070804 _Labos Elemer_, May 08 2002