Tony Forbes writes:
>We all know that A. Hurwitz discovered the Mersenne primes 2^4253 - 1
>and 2^4423 - 1 in 1961.
>
>(i) Were these the first two 1000+ digit primes discovered?
As far as I know, yes (note that M3217, discovered in 1957 by
Hans Riesel, was very close to 1000 decimal digits in length.)
But hey, don't take my word for it - Chris Caldwell has a table
of the largest prime by year of discovery here:
http://www.utm.edu/research/primes/notes/by_year.html
It is interesting to note that only twice in the electronic
computer era has a non-Mersenne prime held the top spot.
>(ii) If that is true, then is it generally accepted that the larger one
>(4423) was discovered first? (The story I heard was that left the
>computer running overnight and when he came to look at the results he
>read the printer output backwards, thus seeing 4423 before 4253.)
John Selfridge recounted this story to me a few years ago at
a Western Number Theory Conference, and this is precisely
what he said. The story makes a lot more sense if you're old
enough to have used accordion-style line printer paper, which
spills into the output bin with the most-recent page on top.
So, it depends on what you mean by "discovered" -
if you mean flagged as prime by a computer then M4253 was
discovered first, if you mean recognized as prime by a human
then M4423 was first. (Caldwell's page also makes this point.)
-Ernst
