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 A039779 #20 Dec 05 2024 10:47:15
%S A039779 1,54,99,112,540,3344,4743,6720,7644,8307,11088,12852,15225,20300,
%T A039779 22320,83160,86304,94944,129504,160208,186992,200640,205712,207264,
%U A039779 266266,280592,331731,364941,383724,404550,441232,445050,447876,449072,454575,458052,497781
%N A039779 Numbers k such that phi(k) is equal to A008473(k).
%H A039779 Amiram Eldar, <a href="/A039779/b039779.txt">Table of n, a(n) for n = 1..866</a> (terms below 10^10)
%e A039779 phi(54) = 18, 54 = 2^1*3^3, (2+1)*(3+3) = 18.
%t A039779 Reap[For[n = 1, n < 500000, n++, If[EulerPhi[n] == Times @@ Plus @@@ FactorInteger[n], Print[n]; Sow[n]]]][[2, 1]] (* _Jean-François Alcover_, May 06 2017 *)
%o A039779 (PARI) is(k) = {my(f = factor(k)); eulerphi(f) == prod(i = 1, #f~, f[i, 1] + f[i, 2]);} \\ _Amiram Eldar_, Dec 04 2024
%Y A039779 Cf. A000010, A008473.
%K A039779 nonn
%O A039779 1,2
%A A039779 _Olivier Gérard_