The status of whether 10 is a friendly number is currently unknown.
Here's a breakdown:
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Friendly Numbers: A number is considered friendly if it shares the same abundancy index as another number. The abundancy index of a number is the ratio of the sum of its divisors to the number itself.
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Known Friendly Numbers: Examples of numbers that are known to be friendly include 6, 12, 24, 28, 30, 40, 42, 56, and 60.
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Solitary Numbers: Numbers that are not friendly are called solitary.
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The Case of 10: Despite research, the friendly status of 10 (and other numbers like 14, 15, and 20) remains undetermined. It hasn't been proven to be either friendly or solitary. As stated in the reference, "...the status of numbers 10, 14, 15, 20, and many others remains unknown."
Therefore, we cannot definitively say whether 10 is a friendly number.
