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)
“Cole’s Hill was the scene of the secret night burials of those who died during the first year of the settlement. Corn was planted over their graves so that the Indians should not know how many of their number had perished.”
—For the State of Massachusetts, U.S. public relief program (1935-1943)