Voilà!
Mersenne's allegation that $2^{67}-1$ is prime was
disproved [well, it had been known for some time
that it's composite, but the present sentence reads more nicely] by
Cole, who
displayed
$2^{67}-1=193707721\times761838257287$ after working "three years of Sundays"
to
discover the fact. The story goes that Cole's lecture reporting the
factorization consisted of his evaluating
$2^{67}-1$, and then laboriously multiplying $193707721\times761838257287$;
et
voilà!
My apology, by the way, for my present inability to translate my \TeX to html. I'll do better soon.
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alf@ics.mq.edu.au : 31 Dec 95