project-euler/Sidef/479 Roots on the Rise.sf

#!/usr/bin/ruby

# Daniel "Trizen" Șuteu
# License: GPLv3
# Date: 21 February 2018
# https://github.com/trizen

# https://projecteuler.net/problem=479

# Runtime: 19.709s (previously: 36.014s)

var n = 1e6
var m = 1000000007

say sum(1..n, {|k|
    with (mulmod(k, k, m) - 1) {|p|
        divmod(p * ((-1)**n * powmod(p, n, m) - 1), p+1, m)
    }
})%m