OFFSET
1,2
LINKS
Harry J. Smith, Table of n, a(n) for n = 1..1000
MATHEMATICA
Select[Table[EulerPhi[n] DivisorSigma[1, n]/n, {n, 2000}], IntegerQ] (* Harvey P. Dale, Mar 17 2020 *)
PROG
(PARI) { n=0; for (m=1, 10^10, if ((a=eulerphi(m)*sigma(m)/m) % 1.0 == 0 , write("b066993.txt", n++, " ", a); if (n==1000, return)) ) } \\ Harry J. Smith, Apr 16 2010
CROSSREFS
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Jan 27 2002
EXTENSIONS
Missing term a(43)=992 and new term a(53)=1482 added by Harry J. Smith, Apr 16 2010
STATUS
approved