OFFSET
1,2
LINKS
Harry J. Smith, Table of n, a(n) for n = 1..1000
FORMULA
EXAMPLE
m=319, phi(319) = 280, sigma(319) = 360; phi(319)*sigma(319) = 100800, phi(319) + sigma(319) = 640; 1/(harmonic mean) =(640/100800)/2, harmonic mean = 315, arithmetic mean = 320, geometric mean is not an integer.
PROG
(PARI) { n=0; for (m=1, 10^9, e=eulerphi(m); s=sigma(m); h=(2*e*s)/(e + s); if (frac(h) == 0, write("b065150.txt", n++, " ", m); if (n==1000, return)) ) } \\ Harry J. Smith, Oct 13 2009
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Oct 18 2001
STATUS
approved