rms(1, ... , 2*k-1)

c.zizka at email.cz c.zizka at email.cz
Thu Sep 4 10:40:32 CEST 2008

In message <3cce05d60809031541m6e6abc31v7ff095e38832647 at mail.gmail.com>,
Alonso Del Arte <alonso.delarte at gmail.com> writes

>> I would not believe _any_ result of someone who thinks that 1 is prime....

>> Peter

>That might tantamount to age discrimination. As late as the 1940s in
>America (and perhaps as late as the 1980s in less industrially
>developed countries) children were taught that 1 is a prime number.
>The OEIS has always acknowledged this, with A008578.

According to the Wikipedia entry on 'Prime Number', most mathematicians
"until the 19th century" considered 1 to be prime; and the change
occurred so that the fundamental theorem of arithmetic could be stated
simply in terms of a "unique factorization into primes". (1 needs to be
excluded, because you can raise it to whatever power you like).

That theorem was first proved by Gauss in 'Disquisitiones Arithmeticae',
written in 1798 and published in 1801, which takes us to the very start
of the 19th century. So, does Gauss call 1 prime or not-prime in

If this was the seminal work which changed the convention, one could say
that 1 stopped being called prime when number theory was born...


Neil Fernandez

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