Friendly Numbers and The Negative Level of the Divisor Function

Описание: Let me tell you about "friendly numbers" and "solitary numbers". Along the way we will meet "multiperfect numbers", level -1 of the divisor function, a mystery about the number 10, and more!

Here are some episodes about semi-related topics I've made in the past:
About aliquot sums and fun nicknames -    • 13 Special Types of Numbers With Strange N...  
About how perfect numbers relate to primes -
   • Hyperelevens (and the Largest Primes Ever ...  

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This episode was filmed by Carlo Trappenberg, and was directed / edited / soundtracked by me (Domotro).
Special thanks to Evan Clark and to all of my Patreon supporters:
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If you want to mail me anything (such as any clocks/dice/etc. that you'd like to see in the background of Grade -2), here's my private mailbox address (not my home address). If you're going to send anything, please watch this short video first:    • Видео  
Domotro
1442 A Walnut Street, Box # 401
Berkeley, CA 94709

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In case anybody searches any of these terms, topics discussed in this video include: the divisor function, sum of divisor function, sigma function, aliquot sums, factors/divisors, proper divisors, perfect numbers, multiperfect numbers, hemiperfect numbers, abundant numbers, deficient numbers, friendly numbers, solitary numbers, cats, squirrels, and lots of other cool things