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| | Harmonic divisor number - Wikipedia, the free encyclopedia |
 | | A harmonic divisor number, or Ore number, is a number whose divisors, averaged in a harmonic mean, results in an integer. |
 | | Three of these listed are also perfect numbers, and like perfect numbers, harmonic divisor numbers tend to be even numbers, at least in the range observed. |
 | | For example, 496 is a harmonic divisor number because 10, its number of divisors, divided by the sum of the reciprocals of its divisors, 1, 2, 4, 8, 16, 31, 62, 124, 248 and 496, (the harmonic mean), yields an integer, 5 in this case. |
| en.wikipedia.org /wiki/Harmonic_divisor_number (160 words) |
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