|
%I #11 Jan 31 2021 13:11:28
%S 1,2,4,9,16,18,64,100,225,242,450,516,729,1458,3872,4096,4624,13932,
%T 14406,17672,18225,20124,21780,28900,29262,29616,36450,45996,62500,
%U 65025,65536,76832,92778,95916,106092,106308,114630,114930
%N Numbers n such that sigma(phi(n)) divides phi(sigma(n)).
%H Donovan Johnson, <a href="/A073858/b073858.txt">Table of n, a(n) for n = 1..1000</a>
%t Select[Range[115000],Divisible[EulerPhi[DivisorSigma[1,#]],DivisorSigma[ 1,EulerPhi[ #]]]&] (* _Harvey P. Dale_, Jan 31 2021 *)
%o (PARI) n=0; for(m=1, 817034100, if(eulerphi(sigma(m))%sigma(eulerphi(m))==0, n++; write("b073858.txt", n " " m))) /* _Donovan Johnson_, Jul 05 2012 */
%Y Cf. A033632, A066930.
%K easy,nonn
%O 1,2
%A _Benoit Cloitre_, Sep 02 2002
|
