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Contents
The Greek mathematican Nicomachus devised a classification scheme for natural numbers, identifying each as belonging uniquely to the categories of _abundant_, _perfect_, or _deficient_. A perfect number equals the sum of its positive divisors — the pairs of numbers whose product yields the target number, excluding the number itself. - Perfect: Sum of factors = number - Abundant: Sum of factors > number - Deficient: Sum of factors < number The Aliquot sum is defined as the sum of the factors of a number not including the number itself. ## Examples - 6 is a perfect number because its divisors are 1, 2, 3 and 6 = 1 + 2 + 3. - 28 is a perfect number because 28 = 1 + 2 + 4 + 7 + 14. - Prime numbers 7, 13, etc are considered deficient in the Nicomachus classification.
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18 entries across 18 versions & 1 rubygems