http://www.stdlib.net/~colmmacc/2009/11/26/period-pain-3/
(http://www.stdlib.net/~colmmacc/2009/09/27/period-pain-part-... http://www.stdlib.net/~colmmacc/2009/09/14/period-pain/ for the background material).
The reasons primes are optimal should be obvious :)
http://www.stdlib.net/~colmmacc/2009/11/26/period-pain-3/
(http://www.stdlib.net/~colmmacc/2009/09/27/period-pain-part-... http://www.stdlib.net/~colmmacc/2009/09/14/period-pain/ for the background material).
The reasons primes are optimal should be obvious :)