OFFSET
1,1
COMMENTS
Only primes (except 9) may qualify.
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
EXAMPLE
phi(29)=28, 28=2^2*7^1, 2*2*7*1=28.
PROG
(PARI) is(n)=my(f=factor(n)); eulerphi(f)==prod(i=1, #f~, f[i, 1]*f[i, 2])-1 \\ Charles R Greathouse IV, Mar 11 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
a(1) inserted by Charles R Greathouse IV, Mar 11 2014
STATUS
approved