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Re: A Good Activity
Posted:
Dec 6, 2012 2:16 PM


On Thu, Dec 6, 2012 at 11:06 AM, Robert Hansen <bob@rsccore.com> wrote: > The other night, my son and I worked out all the primes less than 100. >
One of the "little theorems" or "tricks" on the primes that could come in handy is that all primes greater than 3 are either 1 less or 1 greater than some multiple of 6  the set of all primes greater than 3 is a subset of of the set of all positive integers 6c1 or 6c+1 for all positive integers c. (It makes it easier to recall all the primes up to whatever number  just count up multiples of six and at each count try to recall which of the two numbers in question are composite and which of the two are prime.
I wrote two messages using this fact with respect to primes at sci.math about a decade ago, to share some things I found with respect to the Twin Prime Conjecture:
"Twin prime conjecture restated without reference to primes" http://mathforum.org/kb/message.jspa?messageID=507327
"Re: Twin prime conjecture restated without reference to primes" http://mathforum.org/kb/message.jspa?messageID=507328



