#!/usr/bin/ruby # ## https://rosettacode.org/wiki/Left_factorials#Sidef # func left_fact(k) { sum(^k, { _! }) } [range(0, 10), range(20, 50).by(10)].each { |r| r.each { |i| printf("!%d = %s\n", i, left_fact(i)); } }