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Perfect numbers: Difference between revisions
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{{task|Discrete math}}
Write a function which says whether a number is perfect.
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[[wp:Perfect_numbers|A perfect number]] is a positive integer that is the sum of its proper positive divisors excluding the number itself.
Equivalently, a perfect number is a number that is half the sum ▼
▲Equivalently, a perfect number is a number that is half the sum of all of its positive divisors (including itself).
Note: The faster [[Lucas-Lehmer test]] is used to find primes of the form 2<sup>''n''</sup>-1, all ''known'' perfect numbers can be derived from these primes ▼
using the formula (2<sup>''n''</sup> - 1) × 2<sup>''n'' - 1</sup>. ▼
It is not known if there are any odd perfect numbers (any that exist are larger than 10<sup>2000</sup>).▼
'''See also'''▼
▲Note: The faster [[Lucas-Lehmer test]] is used to find primes of the form <big> 2<sup>''n''</sup>-1</big>, all ''known'' perfect numbers can be derived from these primes
▲It is not known if there are any odd perfect numbers (any that exist are larger than <big>10<sup>2000</sup></big>).
* [[Rational Arithmetic]]
* [[oeis:A000396|Perfect numbers on OEIS]]
* [http://www.oddperfect.org/ Odd Perfect] showing the current status of bounds on odd perfect numbers.
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=={{header|Ada}}==
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