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 A060670 #13 Nov 17 2024 07:19:43
%S A060670 32,132,156,544,912,924,1012,1044,1140,1452,1464,1472,1476,1572,1664,
%T A060670 1764,2076,2100,2232,2424,2580,2624,2652,3096,3248,3336,3444,3660,
%U A060670 3996,4488,4776,4840,5060,5316,5412,5696,6504,6516,6540,6612,6660,6780,6996,7116
%N A060670 Numbers k such that phi(x) = k has exactly 7 solutions.
%H A060670 Amiram Eldar, <a href="/A060670/b060670.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..1000 from T. D. Noe)
%H A060670 Max Alekseyev, <a href="https://oeis.org/wiki/User:Max_Alekseyev/gpscripts">PARI/GP Scripts for Miscellaneous Math Problems</a> (invphi.gp).
%e A060670 32 = phi(51) = phi(64) = phi(68) = phi(80) = phi(96) = phi(102) = phi(120).
%t A060670 a = Table[ 0, {8000} ]; Do[ p = EulerPhi[ n ]; If[ p < 8001, a[ [ p ] ]++ ], {n, 1, 25000} ]; Select[ Range[ 8000 ], a[ [ # ] ] == 7 & ]
%o A060670 (PARI) is(n)=sum(i=1,n,eulerphi(i)==n)==7 \\ _Charles R Greathouse IV_, Mar 03 2014
%o A060670 (PARI) is(k) = invphiNum(k) == 7 \\ _Amiram Eldar_, Nov 17 2024, using _Max Alekseyev_'s invphi.gp
%Y A060670 Cf. A000010.
%Y A060670 Number of solutions: A007617 (0), A007366 (2), A007367 (3), A060667 (4), A060668 (5), A060669 (6), this sequence (7), A060671 (8), A060672 (9), A060673 (10), A060674 (11), A060675 (12).
%K A060670 nonn
%O A060670 1,1
%A A060670 _Robert G. Wilson v_, Apr 18 2001