OFFSET
1,3
COMMENTS
For a prime p, a(p) = phi(p), where phi is Euler's totient function. - Alonso del Arte, Jun 16 2012
LINKS
Harry J. Smith, Table of n, a(n) for n = 1..1000
EXAMPLE
a(10) = 13 because 10 is divisible by the primes 2 and 5, and 10*(1/2 + 4/5) = 13.
PROG
(PARI) { for (n=1, 1000, s=0; p=2; while (p<=n, if(n%p == 0, s+=1 - 1/p); p=nextprime(p + 1)); write("b065968.txt", n, " ", n*s) ) } \\ Harry J. Smith, Nov 05 2009
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Dec 09 2001
STATUS
approved