OFFSET
1,2
LINKS
Donovan Johnson, Table of n, a(n) for n = 1..500
PROG
(PARI) isok(n) = eulerphi(n) == sumdiv(n, d, core(d)); \\ Michel Marcus, Aug 09 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Sep 07 2002
EXTENSIONS
More terms from Michel Marcus, Aug 09 2013
STATUS
approved