project-euler/Sidef/581 47-smooth triangular numbers.sf

#!/usr/bin/ruby

# Daniel "Trizen" Șuteu
# License: GPLv3
# Date: 01 May 2017
# Edit: 28 June 2019
# https://github.com/trizen

# https://projecteuler.net/problem=581

var B     = 47
var limit = 1109496723125   # A002072(π(47)) = A002072(15)

var smooth_numbers = [1]

for p in (primes(2, B)) {
    say "p = #{p}"
    for n in (smooth_numbers) {
        if (n*p <= limit) {
            smooth_numbers << n*p
        }
    }
}

var total = 0

for n in (smooth_numbers) {
    if (is_smooth(n+1, B)) {
        total += n
    }
}

say total