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Topic: 1 as a prime number
Replies: 11   Last Post: Dec 9, 1997 11:13 AM

 Messages: [ Previous | Next ]
 mark snyder Posts: 1,300 Registered: 12/3/04
Re: 1 as a prime number
Posted: Dec 8, 1997 7:22 PM

At 4:00 PM -0500 12/8/97, John Conway wrote:
>On Mon, 8 Dec 1997, mark snyder wrote:
>

>> At 9:58 PM -0200 12/7/97, Julio Gonzalez Cabillon wrote:
>> >At 07:47 PM 05/12/1997 GMT, Mark Snyder wrote:
>> >>I have heard that until about 1800, 1 was considered to be a prime number.
>> >>Is this correct?

>> >
>> >Not quite! JGC

>>
>> So what *is* correct?
>>
>>
>> mark snyder
>>

> I answered this at some length a few days ago. The tradition
>before this century (dating back to Euclid's Elements) was indeed
>to count 1 as a prime, and even Lehmer's 1914 list of prime numbers to
>10 million does so. But the many inconveniences it causes have
>led people this century to put it into a new category, and call
>it a "unit" rather than a prime.
>
> John Conway

And I appreciate the time you took to answer my question. Perhaps I was
not clear on what the question was. I know why it is undesirable to
consider 1 as a prime number, and it is interesting that it was considered
prime by Lehmer as late as 1914. But my question was: when did it became
gradually accepted that we should not consider 1 as a prime number? A
colleague of mine had said that he read somewhere (but didn't remember
where) that 1800 was some kind of watershed in this regard, and what I was
hoping for was some reference where I might read more about the history of
this, hence the post to the math history list. Evidently my colleague was
off by 100 years, but I would still be interested in any references.

And my comment about the "big meeting" was my (evidently feeble) attempt at
jocularity...

mark snyder

Date Subject Author
12/5/97 mark snyder
12/5/97 John Conway
12/7/97 Julio Gonzalez Cabillon
12/8/97 mark snyder
12/8/97 John Conway