func almost_primes(a, b, k) {

    a = max(2**k, a)
    var arr = []

    func (m, lo, k) {

        var hi = idiv(b,m).iroot(k)

        if (k == 1) {

            lo = max(lo, idiv_ceil(a, m))

            each_prime(lo, hi, {|p|
                arr << m*p
            })

            return nil
        }

        each_prime(lo, hi, {|p|

            var t = m*p
            var u = idiv_ceil(a, t)
            var v = idiv(b, t)

            next if (u > v)

            __FUNC__(t, p, k-1)
        })
    }(1, 2, k)

    return arr.sort
}

for k in (1..5) {
    var (x=10, lo=1, hi=2)
    var arr = []
    loop {
        arr += almost_primes(lo, hi, k)
        break if (arr.len >= x)
        lo = hi+1
        hi = 2*lo
    }
    say arr.first(x)
}