project-euler/Sidef/072 Counting fractions.sf

#!/usr/bin/ruby

# Author: Daniel "Trizen" Șuteu
# Date: 15 August 2016
# License: GPLv3
# Website: https://github.com/trizen

# https://projecteuler.net/problem=72

# Runtime: 3.661s (previously 5.425s)

func count_frac(n) {
    sum(2..n, {|k| euler_totient(k) })
}

say count_frac(1e6)