140823(2)

Ruby


約数の和（自身を含む）

require 'mathn'

# a^1+a^2+......a^x
def sum1(i, j)
  power = 1
  sum = 1
  for k in (1..j)
    power *= i
    sum += power
  end
  return sum
end

# (a^1+a^2+......a^x)(b^1+b^2+......b^y)......
def sum2(i)
  sum = 1
  pq = i.prime_division
  pq.each{|tes| sum *= sum1(tes[0], tes[1])}
  return sum
end

p sum2(24)  # 1, 2, 3, 4, 6, 8, 12, 24

出力結果
60