OFFSET
1,2
COMMENTS
The first term that has 3 prime divisors is a(240) = 2*3*5.
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
FORMULA
(log n)/W(log n) < a(n) <= n for n > 1. - Charles R Greathouse IV, Aug 16 2016
EXAMPLE
a(9) = 3 because 9 divides phi(3^3) = 18.
PROG
(PARI) a(n)=my(k = 1); while(eulerphi(k^k) % n, k++); k;
(PARI) a(n)=my(k=1); while(eulerphi(k)*Mod(k, n)^(k-1), k++); k \\ Charles R Greathouse IV, Aug 16 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
Altug Alkan, Aug 16 2016
STATUS
approved