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 A060674 #12 Nov 17 2024 07:20:15
%S A060674 48,512,540,1000,1836,2136,2176,2320,2340,3216,3648,3936,4284,4352,
%T A060674 4356,4784,5088,5640,5936,6216,6576,6816,7120,7224,7280,7752,8100,
%U A060674 8184,8496,8520,8760,9040,9296,9660,9680,9900,9996,10332,10860,11640,11680,11844
%N A060674 Numbers k such that phi(x) = k has exactly 11 solutions.
%H A060674 Amiram Eldar, <a href="/A060674/b060674.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..1000 from T. D. Noe)
%H A060674 Max Alekseyev, <a href="https://oeis.org/wiki/User:Max_Alekseyev/gpscripts">PARI/GP Scripts for Miscellaneous Math Problems</a> (invphi.gp).
%e A060674 48 = phi(65) = phi(104) = phi(105) = phi(112) = phi(130) = phi(140) = phi(144) = phi(156) = phi(168) = phi(180) = phi(210).
%t A060674 a = Table[ 0, {12500} ]; Do[ p = EulerPhi[ n ]; If[ p < 12501, a[ [ p ] ]++ ], {n, 1, 50000} ]; Select[ Range[ 12500 ], a[ [ # ] ] == 11 & ]
%o A060674 (PARI) is(n)=sum(i=1,n,eulerphi(i)==n)==11 \\ _Charles R Greathouse IV_, Mar 03 2014
%o A060674 (PARI) is(k) = invphiNum(k) == 11 \\ _Amiram Eldar_, Nov 17 2024, using _Max Alekseyev_'s invphi.gp
%Y A060674 Cf. A000010.
%Y A060674 Number of solutions: A007617 (0), A007366 (2), A007367 (3), A060667 (4), A060668 (5), A060669 (6), A060670 (7), A060671 (8), A060672 (9), A060673 (10), this sequence (11), A060675 (12).
%K A060674 nonn
%O A060674 1,1
%A A060674 _Robert G. Wilson v_, Apr 18 2001