OFFSET
1,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000 (calculated using data from Jud McCranie)
FORMULA
sigma(k)/phi(k) is integer, sigma(2*k)/phi(2*k) is not.
EXAMPLE
k = 12, 2*k = 24: sigma(12)/phi(12) = 28/4 = 7, while sigma(24)/phi(24) = 60/8 = 15/2.
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Oct 15 2002
STATUS
approved