[Tutor] List comprehension question

[Richard D. Moores]

def proper_divisors(n):
    """
    Return the sum of the proper divisors of positive integer n
    """
    return sum([x for x in range(1,n) if int(n/x) == n/x])

The list comprehension is this function is inefficient in that it computes
n/x twice. I'd like to do an  a = n/x and use a in
"if int(a) == a", but I don't know how.

Thanks,

Dick Moores
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