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 A069058 #30 May 22 2022 14:16:33 %S A069058 1,18,72,162,648,1152,1458,4608,5832,10368,13122,41472,52488,73728, %T A069058 93312,118098,294912,373248,472392,663552,839808,1062882,2654208, %U A069058 3359232,4251528,4718592,5971968,7558272,9565938,18874368,23887872 %N A069058 Numbers n such that A017666(n)=phi(n). %C A069058 Appears to be a subset of A195321, i.e. all terms greater than 1 are of the form 18*n^2. - _William J. Keith_, May 25 2016 %C A069058 It also appears to be a subset of A003586, i.e., all the terms below 10^12 are of the form 2^i*3^j. - _Giovanni Resta_, May 26 2016 %H A069058 Giovanni Resta, <a href="/A069058/b069058.txt">Table of n, a(n) for n = 1..81</a> (terms < 10^12) %t A069058 Select[Range[10^6], Denominator@ Total[1/Divisors@ #] == EulerPhi@ # &] (* _Michael De Vlieger_, May 25 2016 *) %o A069058 (PARI) for(n=1, 2500000, if(denominator(sumdiv(n,k,1/k)) == eulerphi(n), print1(n,","))) %o A069058 (PARI) isok(n) = denominator(sigma(n)/n) == eulerphi(n); \\ _Michel Marcus_, May 26 2016 %Y A069058 Cf. A195321. %K A069058 easy,nonn %O A069058 1,2 %A A069058 _Benoit Cloitre_, Apr 04 2002 %E A069058 More terms from _Rick L. Shepherd_, Apr 16 2002