Euclid's formula/Perfect Numbers #2

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In summary, to prove that the sum of the reciprocals of all divisors of a perfect number is equal to 2, we can use Euclid's formula for perfect numbers and observe that each reciprocal can be written as d/n, where d is a divisor of n. By adding all these reciprocals, we get 2, which is equal to the sum of all divisors of a perfect number.
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Homework Statement



Prove that the sum of the reciprocals of all divisors of a perfect number is equal to 2.

Homework Equations



Euclid's formula for perfect #'s

The Attempt at a Solution



I am so lost.
 
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  • #2
Let d1, d2,..., dk be a (ordered) list of divisors of perfect number n where d1 = 1, dk = n. It is clear that the sum of all these divisors is 2n.

Observe that d1dk = n implies d1 = n/dk, which in turn implies that 1/d1 = dk/n.

Do this same thing for d2dk-1 = n implies... etc
Now you have each reciprocal written as d/n where d is a divisor of n, so add them up.
 

FAQ: Euclid's formula/Perfect Numbers #2

What is Euclid's formula?

Euclid's formula is a mathematical formula, named after the Greek mathematician Euclid, used to find perfect numbers. It states that if 2^(p-1)(2^p-1) is a prime number, then (2^p-1)(2^(p-1)) is a perfect number, where p is a prime number.

How is Euclid's formula related to perfect numbers?

Euclid's formula is used to find perfect numbers, which are numbers that are equal to the sum of their proper divisors. This formula helps in determining which prime numbers can produce perfect numbers.

What are perfect numbers?

Perfect numbers are positive integers that are equal to the sum of their proper divisors. The first four perfect numbers are 6, 28, 496, and 8128.

How many perfect numbers are known to exist?

As of 2021, 51 perfect numbers have been discovered. It is not known if there are an infinite number of perfect numbers, but it is believed that there are only a finite number of them.

What is the significance of perfect numbers in mathematics?

Perfect numbers have been studied since ancient times and have intrigued mathematicians for centuries. They have connections to various mathematical concepts, such as prime numbers and Mersenne primes. They also have applications in areas such as cryptography and coding theory.

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