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 A060671 #13 Nov 17 2024 07:19:52
%S A060671 36,64,176,200,224,280,324,464,520,888,920,1184,1368,1400,1520,1696,
%T A060671 1720,1904,1960,2040,2096,2120,2256,2392,2600,2656,2712,2752,2864,
%U A060671 2944,2960,2968,2976,2988,3104,3276,3300,3408,3616,3640,3792,3800,3816,3824,3880
%N A060671 Numbers k such that phi(x) = k has exactly 8 solutions.
%H A060671 Amiram Eldar, <a href="/A060671/b060671.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..1000 from T. D. Noe)
%H A060671 Max Alekseyev, <a href="https://oeis.org/wiki/User:Max_Alekseyev/gpscripts">PARI/GP Scripts for Miscellaneous Math Problems</a> (invphi.gp).
%e A060671 36 = phi(37) = phi(57) = phi(63) = phi(74) = phi(76) = phi(108) = phi(114) = phi(126).
%t A060671 a = Table[ 0, {5000} ]; Do[ p = EulerPhi[ n ]; If[ p < 5001, a[ [ p ] ]++ ], {n, 1, 25000} ]; Select[ Range[ 5000 ], a[ [ # ] ] == 8 & ]
%o A060671 (PARI) is(n)=sum(i=1,n,eulerphi(i)==n)==8 \\ _Charles R Greathouse IV_, Mar 03 2014
%o A060671 (PARI) is(k) = invphiNum(k) == 8 \\ _Amiram Eldar_, Nov 17 2024, using _Max Alekseyev_'s invphi.gp
%Y A060671 Cf. A000010.
%Y A060671 Number of solutions: A007617 (0), A007366 (2), A007367 (3), A060667 (4), A060668 (5), A060669 (6), A060670 (7), this sequence (8), A060672 (9), A060673 (10), A060674 (11), A060675 (12).
%K A060671 nonn
%O A060671 1,1
%A A060671 _Robert G. Wilson v_, Apr 18 2001