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 A067383 #12 Sep 08 2024 17:30:52 %S A067383 181,899,2501,4687,10991,12989,17653,25199,25853,26549,26657,54473, %T A067383 65941,68381,72007,82777,96197,98903,102719,116449,124013,135907, %U A067383 150121,169153,188917,193553,201173,207461,219559,234301,237961,239279 %N A067383 Numbers n such that sigma(phi(n))/sigma(n) = 3. %H A067383 Donovan Johnson, <a href="/A067383/b067383.txt">Table of n, a(n) for n = 1..1000</a> %t A067383 For[ n=1, True, n++, If[ DivisorSigma[ 1, EulerPhi[ n ] ]/DivisorSigma[ 1, n ]==3, Print[ n ] ] ] %t A067383 Select[Range[250000],DivisorSigma[1,EulerPhi[#]]/DivisorSigma[1,#]==3&] (* _Harvey P. Dale_, Sep 08 2024 *) %o A067383 (PARI) is(n)=sigma(eulerphi(n=factor(n)))/sigma(n)==3 \\ _Charles R Greathouse IV_, Nov 27 2013 %Y A067383 Cf. A033631, A066831, A067382, A067384, A067385, A197952. %K A067383 nonn %O A067383 1,1 %A A067383 _Dean Hickerson_, Jan 20 2002