Perfect numbers: Difference between revisions
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A number is perfect if the sum of its factors is equal to twice the number. An equivalent condition is that <tt>n</tt> is perfect if the sum of <tt>n</tt>'s factors that are less than <tt>n</tt> is equal to <tt>n</tt>. |
A number is perfect if the sum of its factors is equal to twice the number. An equivalent condition is that <tt>n</tt> is perfect if the sum of <tt>n</tt>'s factors that are less than <tt>n</tt> is equal to <tt>n</tt>. |
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Note: The faster [[Lucas-Lehmer test]] is used to find primes of the form 2<sup>''n''</sup>-1, all ''known'' perfect numbers can 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. |
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. |
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===See also=== |
===See also=== |
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