divisors_less_than_k.sf

#!/usr/bin/ruby

# Daniel "Trizen" Șuteu
# Date: 04 August 2019
# https://github.com/trizen

# Generate all the divisors d of n, such that d <= k.

func divisors_le (n, k) {

    var d  = [1]
    var pp = n.factor_exp.grep{ _[0] <= k }

    for p,e in (pp) {
        var r = 1
        d << gather {
            e.times {
                r *= p
                d.each { |u|
                    take(u*r) if (u*r <= k)
                }
            }
        }...
    }

    d.sort
}

# Generate the divisors of 5040 less than or equal to 42
say divisors_le(5040, 42)