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 A071389 #16 Nov 11 2024 05:22:19
%S A071389 1,2,8,32,48,396,72,216,1056,1320,240,480,15936,3072,7344,2016,3024,
%T A071389 9984,22848,3360,13248,9360,4800,9504,9216,23328,7680,53280,12480,
%U A071389 29376,91200,159744,22464,228960,29952,179200,47040,68544,15840,20736,61440
%N A071389 Least number m such that cardinality of InvPhi(m) = prime(n).
%H A071389 Amiram Eldar, <a href="/A071389/b071389.txt">Table of n, a(n) for n = 1..1000</a>
%H A071389 Max Alekseyev, <a href="https://oeis.org/wiki/User:Max_Alekseyev/gpscripts">PARI/GP Scripts for Miscellaneous Math Problems</a> (invphi.gp).
%F A071389 a(n) = Min{x; Card(InvPhi(x)) = prime(n), n-th prime}
%e A071389 For n = 11: prime(11) = 31, Card(InvPhi(x)) = 31 for {240, 672, ...}; the smallest is 240 = a(11).
%o A071389 (PARI) lista(len) = {my(p = prime(len), v = vector(p, i, -!isprime(i)), c = 0, k = 1, i); while(c < len, i = invphiNum(k); if(i > 0 && i <= p && v[i] == 0, c++; v[i] = k); k++); select(x -> x > 0, v);} \\ _Amiram Eldar_, Nov 11 2024, using _Max Alekseyev_'s invphi.gp
%Y A071389 Cf. A000010, A014197, A058277, A063512, A071386, A071387, A071388.
%K A071389 nonn
%O A071389 1,2
%A A071389 _Labos Elemer_, May 23 2002
%E A071389 4 more terms from _Emeric Deutsch_, Jul 25 2005
%E A071389 More terms from _Max Alekseyev_, Apr 24 2010