p=any number ending in 3

check p is not a square

where a+b is a factor and a-b is another factor

Number ending in 3: factors end in 1 and 3, or 7 and 9. Times by 27 factors now end in 1 and 1.

f=10c+1 L=10d+1

b=(10c+1-10d-1)/2=5(c-d)

Did you read post #11? Using Einstein to demean a member is clever but still not allowed. Please stop deleting your posts and my additions in those posts.

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I have received two complaints about this thread and that is three too many.

Sir Isaac Newton wrote:

Tact is the art of making a point without making an enemy.

@Nehushtan: Please try to think of the other guys feelings when you respond. No more "rubbish" comments.

@Primenumbers: Please try to be more receptive when someone points out a possible error. Supposedly you are posting so that you can get feedback on your work. This is valuable to us all. Welcome criticism when you get it, this is how we all learn.

So I say, calm down everyone. Everyone knows the rules and everyone knows me.

]]>]]>For a prime the only factors will be 1 and itself, so the only occurrence for a squared minus b squared will be when a=(p+1)/2 and b=(p-1)/2. For a composite b will be less than this.

I don't really know how to do this. 4k+2 will always be even so n will be any odd no. My formula doesn't work for even no.'s. So n has factors f and L where a=(f+L) /2 and b=(f-L) /2. For a prime the only factors will be 1 and itself, so the only occurrence for a squared minus b squared will be when a=(p+1)/2 and b=(p-1)/2. For a composite b will be less than this.

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PRIME NUMBERS WROTE

" p= any prime number ending with 3. Check p is not a square." This is redundant. No square will end with 3.

Another way of proving p is prime is;

only when a-b=1So add possible to p and see if it = a square.

(a+b) and (a-b) will be factors

This is because for any odd Non-Prime that has a factor of >1, it can be produced with the below formula;

I can prove it

x = (f + L)/2

y = (f - L)/2 therefore

minus the two and it = fL which are the two factors....

And x - y = ((f + L)/2) - ((f - L)/2) = L which must be >1 for p to Not be, Prime or 1.]]>

check p is not a square

where a+b is a factor and a-b is another factor

if p is prime you will not find any factors

if p is composite you will find factors.

Example:

p=33

27*33=891

46+35=81=27*3 46-35=11

factors for 33 are 3 and 11]]>