Euler_21.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 sumofdivisors(n):
    total_sum = 0
    for i in range(1, n//2+1):
        if n % i == 0:
            total_sum += i
    return total_sum


def find_amicable(max):
    sum = 0
    for i in range(1, max):
        temp = sumofdivisors(i)
        if temp > i and sumofdivisors(temp) == i:
            sum += i + temp

    return sum


summa = find_amicable(10000)
print(summa)