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Friday, September 9, 2016

Symmetry method to find Primes.

By observation I found this method to find primes which can be proofed easily.

THEOREM

For every p_n & a that satisfy p_n < p_n\#-a < p_{n+1}^2 where (a > p_n)

If (a) is a prime then (p_n\#-a) is also a prime

and if (p_n\#-a) is a prime then (a) is possible a prime

Example:
a=2213 (prime number)

let p_n any prime satisfy the above

for instance p_5=11 then p_5\#=2310

11<2310-2213<13*13

11<97<169 it's OK

Then 97 must be a prime.

THE PROOF

(a) and (p_n\#-a) are symmetrical around \frac {p_n\#}{2}

Let a=\frac {p_n\#}{2}+b then (p_n\#-a)=\frac {p_n\#}{2}-b

p_n\#=(\frac {p_n\#}{2}+b)+(\frac {p_n\#}{2}-b)

assume that (\frac {p_n\#}{2}+b) is divisible by \{p_k : p_k \le p_n\}

then (\frac {p_n\#}{2}-b) must be divisible by p_k too

because \frac {p_n\#}{2} is always divisible by any prime 2 < p_k \le p_n so if (+b) is divisible by p_k then (-b) is divisible as well. and if (\frac {p_n\#}{2}+b) is not divisible by any prime of \{p_k : p_k \le p_n\} then (\frac {p_n\#}{2}-b) should be also not divisible by the same prime. So we have this range which we can define the symmetry of the numbers that are not divisible by \{p_k : p_k \le p_n\}. that range is from (p_n+1) to (p_n\#-(p_n+1)) then a should always greater than p_n (a > p_n)

but unfortunately this range of symmetry is broken by the primes greater than p_n because p_n\# is not divisible by p_{n+1} and greater.

So the limits of symmetry ,which can not be affected by the primes greater than p_n , can be defined between p_n and p_{n+1}^2

So if (p_n\#-a) satisfy p_n \lt p_n\#-a \lt p_{n+1}^2 then it is in the range of symmetry and if (a) is prime then (p_n\#-a) is also prime

but if (p_n\#-a) is prime then (a) could be prime because it will not be divisible by \{ p_k : p_k \le p_n\} but on the other hand it could be divisible by the primes greater than p_n because it is may located out of the range where the symmetry is broken.


We can notice the symmetry in these extra examples

1) For p_3\#=2*3*5=30
p_{n+1}^2=7∗7=49
so all the primes 5 < p < 30 are symmetrical around 15 \frac {p_n\#}{2}=15 note that 15±2 , 15±4 , 15±8 are all primes.

2) For p_4=210 p_{n+1}^2=11∗11=121, number 121 is less than 210 which will break the symmetry starting from 121 so the range that will maintain the symmetry is (7 < 210-a < 121) , a > 7
\frac {p_n\#}{2}=105 note that 105±2 , 105±4 , 105±8 are primes etc...
Let a=151 (prime number) then 210-151=59
7 < 59 < 121 then 59 is a prime.

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