OFFSET
1,1
LINKS
Charles R Greathouse IV and Donovan Johnson, Table of n, a(n) for n = 1..1000 (first 500 terms from Charles R Greathouse IV)
MAPLE
with(numtheory); A067238:=n->`if`(sigma(n)=bigomega(n)*phi(n), n, NULL); seq(A067238(n), n=1..10^6); # Wesley Ivan Hurt, Nov 21 2013
PROG
(PARI) isok(n) = sigma(n) == bigomega(n)*eulerphi(n); \\ Michel Marcus, Nov 21 2013
(PARI) is(n)=n=factor(n); sigma(n)==bigomega(n)*eulerphi(n) \\ Charles R Greathouse IV, Nov 21 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Feb 20 2002
STATUS
approved