OFFSET
1,2
COMMENTS
Does sequence consist of 1,3 and all powers of 5? Answer from _Lambert Klasen_, Oct 07 2005: Yes! See attached file.
LINKS
Lambert Klasen, Notes on A074701
MAPLE
with(numtheory): a:=proc(n) local div: div:=convert(divisors(phi(n)), list): if add(mobius(phi(div[j]))*phi(n)/div[j], j=1..nops(div))=n then n else fi end: seq(a(n), n=1..5000); # Emeric Deutsch, Mar 27 2005
PROG
(PARI) isok(n) = n == sumdiv(eulerphi(n), d, moebius(eulerphi(d))*eulerphi(n)/d); \\ Michel Marcus, Aug 15 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Sep 03 2002
EXTENSIONS
2 more terms from Emeric Deutsch, Mar 27 2005
STATUS
approved