In number theory, a deficient number or defective number is a number n for which the sum of divisors σ(n)<2n, or, equivalently, the sum of proper divisors (or aliquot sum) s(n)<n. The value 2n − σ(n) (or n − s(n)) is called the number's deficiency.
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Famous quotes containing the words deficient and/or number:
“Regularity and Decorum. ‘Tis what we women-authors, in particular, have been thought greatly deficient in; and I should be concerned to find it an objection not to be removed.”
—Elizabeth Cooper (fl. 1730s)
“A considerable percentage of the people we meet on the street are people who are empty inside, that is, they are actually already dead. It is fortunate for us that we do not see and do not know it. If we knew what a number of people are actually dead and what a number of these dead people govern our lives, we should go mad with horror.”
—George Gurdjieff (c. 1877–1949)