Why does
S(5)=5+6=11
?
Is that a mistake?
The prime factors of 6 are 2x3 which add up to 5
But why 5? The only prime factors of 5 are 1 and 5 which add up to 6, not 5.
I would have thought S(5) was just 6.
Problem 618
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Problem 618
Last edited by RobertStanforth on Sat Jan 20, 2018 9:43 pm, edited 1 time in total.
Reason: Renaming for consistency
Reason: Renaming for consistency
Re: PE 618
The number 1 is not a prime. The only prime factor of 5 is itself, which is true for all primes.
Otherwise you would have 5 = 1*5 = 1*1*5 = ..., so the prime factorization would not be unique, which would complicate many definitions.
In the past 1 was often considered a prime. See Wikipedia for a bit of interesting history. Seems like Euler was ahead of his time in this as well.
Otherwise you would have 5 = 1*5 = 1*1*5 = ..., so the prime factorization would not be unique, which would complicate many definitions.
In the past 1 was often considered a prime. See Wikipedia for a bit of interesting history. Seems like Euler was ahead of his time in this as well.
Technically, everyone is full of himself.

 Posts: 98
 Joined: Sat Aug 29, 2009 7:49 pm
Re: PE 618
Another good link is https://en.wikipedia.org/wiki/Fundament ... arithmetic .