Python
def sum_of_divisors(n):
s = 1
i = 2
while i * i <= n:
if n % i == 0:
if i * i == n:
s += i
else:
s += i + n // i
i += 1
return s
def is_abundant(n):
return sum_of_divisors(n) > n
LIMIT = 28123
abundant_list = list(filter(is_abundant, range(2, LIMIT)))
abundant_set = set()
for idx1 in range(len(abundant_list)):
if abundant_list[idx1] > (LIMIT // 2):
break
for idx2 in range(idx1, len(abundant_list)):
n = abundant_list[idx1] + abundant_list[idx2]
if n <= LIMIT:
abundant_set.add(n)
else:
break
print(sum(range(1, LIMIT + 1)) - sum(abundant_set))
