I didn't understand what made this illegal from the article, but http://primes.utm.edu/glossary/page.php?sort=Illegal http://primes.utm.edu/glossary/page.php?so

I didn't understand what made this illegal from the article, but http://primes.utm.edu/glossary/page.php?sort=Illegal http://primes.utm.edu/glossary/page.php?sort=Illegal covers it in more detail. Very interesting.