p021.py

'''
Let d(n) be defined as the sum of proper divisors of n (numbers less than n which divide evenly into n).
If d(a) = b and d(b) = a, where a ≠ b, then a and b are an amicable pair and each of a and b are called amicable numbers.

For example, the proper divisors of 220 are 1, 2, 4, 5, 10, 11, 20, 22, 44, 55 and 110; therefore d(220) = 284. The proper divisors of 284 are 1, 2, 4, 71 and 142; so d(284) = 220.

Evaluate the sum of all the amicable numbers under 10000.
'''


def d(n):
  result = 0
  for i in range(1,n):
    if n % i == 0:
      result += i
  return result
def getSumOfAmicableNumbers():
  result = 0
  a = 0
  while a < 10000:
    b = d(a)
    if d(b) == a and a != b:
      result += a + b
      a = b + 1
    else:
      a += 1
  return result
print(getSumOfAmicableNumbers())