20181104, 17:42  #1 
"Rashid Naimi"
Oct 2015
Remote to Here/There
1946_{10} Posts 
+/ 6 Primality Test
Hi all,
Is there an efficient way of primality testing p+6 and/or p6 when it is known that p is prime or otherwise (more generally) all its factors are known? I am assuming that there is not even for any special forms. Thank you for your time. ETA I am only interested in deterministic tests here. Last fiddled with by a1call on 20181104 at 17:52 
20181104, 18:02  #2 
"Serge"
Mar 2008
Phi(4,2^7658614+1)/2
9,161 Posts 
"Walk before running", some people say.
What's wrong with +/2 Primality Test? Or are you saying that this one is too easy? 
20181104, 18:24  #3 
"Rashid Naimi"
Oct 2015
Remote to Here/There
2×7×139 Posts 
I don't have a solution for either but for what I am working on +/6 shortcut would be useful while +/2 won't be of any use. Any prime +/2 will have one of them with a factor of 3 and won't be prime (5 not withstanding). Not so with 6.
Last fiddled with by a1call on 20181104 at 18:28 
20181104, 18:58  #4  
"Forget I exist"
Jul 2009
Dumbassville
8,369 Posts 
Quote:
is not 6*((6*j+1)*i+j)+1 or 6*((6*j1)*i+j)1or 6*((6*j1)*ij)+1 enjoy Last fiddled with by science_man_88 on 20181104 at 18:58 

20181104, 19:18  #5 
"Rashid Naimi"
Oct 2015
Remote to Here/There
11110011010_{2} Posts 
Interesting algorithm SM. Thank you for introducing me to it.
But I suspect that won't be of direct use for record primes. In particular I assume some of the record (Mersenne perhaps) primes are (not highly but still) likely to have neighboring primes that are 6 off. Knowing that they are prime does not seem to have been useful in proving therm prime. I recall the board members here checking to see if the M50 was twin before publication. I assume if it was they would have been restricted to usual primality tests based on +/1 factoring independent of M50 being prime. Last fiddled with by a1call on 20181104 at 19:19 
20181104, 19:27  #6  
"Forget I exist"
Jul 2009
Dumbassville
8,369 Posts 
Quote:
to have members a(n) such that a(n)1 or a(n)+1 create primes. 

20181104, 19:49  #7 
"Rashid Naimi"
Oct 2015
Remote to Here/There
79A_{16} Posts 
Nah, that's not it. If you must know I am working on projecting triples of primes which are 6 off into twins. It's work in progress and I am too lazy to continue right now.
If you (or anyone else for that matter) can find any prior research in the area, I would appreciate a reference to save me time. 
20181104, 21:56  #8  
"Forget I exist"
Jul 2009
Dumbassville
8,369 Posts 
Quote:
(6*Mod(0,5)+1,6*Mod(1,5)+1,6*Mod(2,5)+1) (6*Mod(1,5)+1,6*Mod(2,5)+1,6*Mod(3,5)+1) (6*Mod(2,5)1,6*Mod(3,5)1,6*Mod(4,5)1) (6*Mod(3,5)1,6*Mod(4,5)1,6*Mod(0,5)1) 

20181104, 21:57  #9 
Feb 2017
Nowhere
3·19·67 Posts 
It's gratuitously confusing to use p for a prime  then say "or otherwise."
We have n  a, n, n + a is an "admissible triple" in the sense of the "prime ktuples conjecture" when x^3  a^2*x is not automatically divisible by some prime. Since the characteristic polynomial of the field of p elements is x^p  x, here we can only have x^3  a^2*x automatically divisible by p = 2 or 3. If a is not divisible by 2, x^3  a^2*x == a^3  x (mod 2) which is divisible by x^2  x; hence x^2  a^2*x is always even. Thus, in order for n  a, n, n + a to be admissible, a must be even. If a is not divisible by 3, then a^2 == 1 (mod 3) and x^3  a^2*x == x^3  x (mod 3), so x^2  a^2*x is divisible by 3. So in order to be admissible, a must be divisible by 3. If a is divisible by 6, then n  a, n, n + a is admissible. According to the prime ktuples conjecture, the number of n's up to X for which all three of n  a, n, n + a are prime, is, asymptotically, a constant (which depends on a) times X/(ln(X))^3. Now the pair n  a, n + a is also admissible (in fact, this pair is admissible for any positive integer a, but let's stick to a divisible by 6). In this case, the conjecture says that the number of n's up to X for which both n  a and n + a are prime, is asymptotically a constant (which depends on a) times X/(ln(X))^2. So, the number of prime pairs n  a, n + a is likely much greater than the number of prime triples n  a, n, n + a, assuming 6a. It's almost certainly greater if gcd(6,a) < 6 :D I doubt knowing the factorization of n has much bearing on deciding whether n  a and n + a are both prime. What I would look at, is eliminating n's for which either n  a or n + a have any small prime factors. 
20181104, 23:21  #10 
"Rashid Naimi"
Oct 2015
Remote to Here/There
11110011010_{2} Posts 
I will have to get back to work tomorrow. So if anyone can finish solving the algorithm be my guest.
PARIGP Code: Code:
\\CJZ100B TwinPrime Generator based on Wilson's Theorem & my infamous Theorem 1 by Rashid Naimi p=6 forprime (q=19^0,19^5,{ \\print(q); a=((q2)!1)/q; if(gcd(ap,(q2)!)<2 && gcd(a+p,(q2)!)<2, c=(a+p)*q(q2)!; d=(q2)!(ap)*q; print("\n**** Found TwinPrimes based on Prime ",q," ****"); print("** ",c," & ",d," **"); ); }) Code:
**** Found TwinPrimes based on Prime 2 **** ** 11 & 13 ** **** Found TwinPrimes based on Prime 3 **** ** 17 & 19 ** **** Found TwinPrimes based on Prime 5 **** ** 29 & 31 ** **** Found TwinPrimes based on Prime 7 **** ** 41 & 43 ** **** Found TwinPrimes based on Prime 17 **** ** 101 & 103 ** **** Found TwinPrimes based on Prime 23 **** ** 137 & 139 ** **** Found TwinPrimes based on Prime 47 **** ** 281 & 283 ** **** Found TwinPrimes based on Prime 103 **** ** 617 & 619 ** **** Found TwinPrimes based on Prime 107 **** ** 641 & 643 ** **** Found TwinPrimes based on Prime 137 **** ** 821 & 823 ** **** Found TwinPrimes based on Prime 283 **** ** 1697 & 1699 ** **** Found TwinPrimes based on Prime 313 **** ** 1877 & 1879 ** **** Found TwinPrimes based on Prime 347 **** ** 2081 & 2083 ** **** Found TwinPrimes based on Prime 373 **** ** 2237 & 2239 ** **** Found TwinPrimes based on Prime 397 **** ** 2381 & 2383 ** **** Found TwinPrimes based on Prime 443 **** ** 2657 & 2659 ** **** Found TwinPrimes based on Prime 467 **** ** 2801 & 2803 ** **** Found TwinPrimes based on Prime 577 **** ** 3461 & 3463 ** **** Found TwinPrimes based on Prime 593 **** ** 3557 & 3559 ** **** Found TwinPrimes based on Prime 653 **** ** 3917 & 3919 ** **** Found TwinPrimes based on Prime 773 **** ** 4637 & 4639 ** **** Found TwinPrimes based on Prime 787 **** ** 4721 & 4723 ** **** Found TwinPrimes based on Prime 907 **** ** 5441 & 5443 ** **** Found TwinPrimes based on Prime 1033 **** ** 6197 & 6199 ** **** Found TwinPrimes based on Prime 1117 **** ** 6701 & 6703 ** **** Found TwinPrimes based on Prime 1423 **** ** 8537 & 8539 ** **** Found TwinPrimes based on Prime 1433 **** ** 8597 & 8599 ** **** Found TwinPrimes based on Prime 1613 **** ** 9677 & 9679 ** **** Found TwinPrimes based on Prime 1823 **** ** 10937 & 10939 ** **** Found TwinPrimes based on Prime 2027 **** ** 12161 & 12163 ** **** Found TwinPrimes based on Prime 2063 **** ** 12377 & 12379 ** **** Found TwinPrimes based on Prime 2137 **** ** 12821 & 12823 ** **** Found TwinPrimes based on Prime 2153 **** ** 12917 & 12919 ** **** Found TwinPrimes based on Prime 2203 **** ** 13217 & 13219 ** **** Found TwinPrimes based on Prime 2287 **** ** 13721 & 13723 ** **** Found TwinPrimes based on Prime 2293 **** ** 13757 & 13759 ** **** Found TwinPrimes based on Prime 2333 **** ** 13997 & 13999 ** **** Found TwinPrimes based on Prime 2347 **** ** 14081 & 14083 ** **** Found TwinPrimes based on Prime 2677 **** ** 16061 & 16063 ** **** Found TwinPrimes based on Prime 2903 **** ** 17417 & 17419 ** **** Found TwinPrimes based on Prime 3257 **** ** 19541 & 19543 ** **** Found TwinPrimes based on Prime 3307 **** ** 19841 & 19843 ** **** Found TwinPrimes based on Prime 3407 **** ** 20441 & 20443 ** **** Found TwinPrimes based on Prime 3413 **** ** 20477 & 20479 ** **** Found TwinPrimes based on Prime 3593 **** ** 21557 & 21559 ** **** Found TwinPrimes based on Prime 3623 **** ** 21737 & 21739 ** **** Found TwinPrimes based on Prime 3673 **** ** 22037 & 22039 ** **** Found TwinPrimes based on Prime 3923 **** ** 23537 & 23539 ** **** Found TwinPrimes based on Prime 4153 **** ** 24917 & 24919 ** **** Found TwinPrimes based on Prime 4217 **** ** 25301 & 25303 ** **** Found TwinPrimes based on Prime 4447 **** ** 26681 & 26683 ** **** Found TwinPrimes based on Prime 4547 **** ** 27281 & 27283 ** **** Found TwinPrimes based on Prime 4597 **** ** 27581 & 27583 ** **** Found TwinPrimes based on Prime 4657 **** ** 27941 & 27943 ** **** Found TwinPrimes based on Prime 5023 **** ** 30137 & 30139 ** **** Found TwinPrimes based on Prime 5197 **** ** 31181 & 31183 ** **** Found TwinPrimes based on Prime 5387 **** ** 32321 & 32323 ** **** Found TwinPrimes based on Prime 5407 **** ** 32441 & 32443 ** **** Found TwinPrimes based on Prime 5693 **** ** 34157 & 34159 ** **** Found TwinPrimes based on Prime 5717 **** ** 34301 & 34303 ** **** Found TwinPrimes based on Prime 5807 **** ** 34841 & 34843 ** **** Found TwinPrimes based on Prime 5827 **** ** 34961 & 34963 ** **** Found TwinPrimes based on Prime 6373 **** ** 38237 & 38239 ** **** Found TwinPrimes based on Prime 6673 **** ** 40037 & 40039 ** **** Found TwinPrimes based on Prime 6857 **** ** 41141 & 41143 ** **** Found TwinPrimes based on Prime 6863 **** ** 41177 & 41179 ** **** Found TwinPrimes based on Prime 6997 **** ** 41981 & 41983 ** **** Found TwinPrimes based on Prime 7297 **** ** 43781 & 43783 ** **** Found TwinPrimes based on Prime 7523 **** ** 45137 & 45139 ** **** Found TwinPrimes based on Prime 7963 **** ** 47777 & 47779 ** **** Found TwinPrimes based on Prime 8377 **** ** 50261 & 50263 ** **** Found TwinPrimes based on Prime 8573 **** ** 51437 & 51439 ** **** Found TwinPrimes based on Prime 9067 **** ** 54401 & 54403 ** **** Found TwinPrimes based on Prime 9203 **** ** 55217 & 55219 ** **** Found TwinPrimes based on Prime 9277 **** ** 55661 & 55663 ** **** Found TwinPrimes based on Prime 9413 **** ** 56477 & 56479 ** **** Found TwinPrimes based on Prime 9433 **** ** 56597 & 56599 ** **** Found TwinPrimes based on Prime 9767 **** ** 58601 & 58603 ** **** Found TwinPrimes based on Prime 9907 **** ** 59441 & 59443 ** **** Found TwinPrimes based on Prime 10357 **** ** 62141 & 62143 ** **** Found TwinPrimes based on Prime 10973 **** ** 65837 & 65839 ** **** Found TwinPrimes based on Prime 11483 **** ** 68897 & 68899 ** **** Found TwinPrimes based on Prime 11743 **** ** 70457 & 70459 ** **** Found TwinPrimes based on Prime 11807 **** ** 70841 & 70843 ** **** Found TwinPrimes based on Prime 11813 **** ** 70877 & 70879 ** **** Found TwinPrimes based on Prime 11833 **** ** 70997 & 70999 ** **** Found TwinPrimes based on Prime 12037 **** ** 72221 & 72223 ** **** Found TwinPrimes based on Prime 12227 **** ** 73361 & 73363 ** **** Found TwinPrimes based on Prime 12757 **** ** 76541 & 76543 ** **** Found TwinPrimes based on Prime 13163 **** ** 78977 & 78979 ** **** Found TwinPrimes based on Prime 13463 **** ** 80777 & 80779 ** **** Found TwinPrimes based on Prime 14087 **** ** 84521 & 84523 ** **** Found TwinPrimes based on Prime 14143 **** ** 84857 & 84859 ** **** Found TwinPrimes based on Prime 14303 **** ** 85817 & 85819 ** **** Found TwinPrimes based on Prime 14537 **** ** 87221 & 87223 ** **** Found TwinPrimes based on Prime 14593 **** ** 87557 & 87559 ** **** Found TwinPrimes based on Prime 14723 **** ** 88337 & 88339 ** **** Found TwinPrimes based on Prime 14983 **** ** 89897 & 89899 ** **** Found TwinPrimes based on Prime 15073 **** ** 90437 & 90439 ** **** Found TwinPrimes based on Prime 15137 **** ** 90821 & 90823 ** **** Found TwinPrimes based on Prime 15493 **** ** 92957 & 92959 ** **** Found TwinPrimes based on Prime 15733 **** ** 94397 & 94399 ** **** Found TwinPrimes based on Prime 15907 **** ** 95441 & 95443 ** **** Found TwinPrimes based on Prime 16193 **** ** 97157 & 97159 ** **** Found TwinPrimes based on Prime 16217 **** ** 97301 & 97303 ** **** Found TwinPrimes based on Prime 16427 **** ** 98561 & 98563 ** **** Found TwinPrimes based on Prime 17033 **** ** 102197 & 102199 ** **** Found TwinPrimes based on Prime 17467 **** ** 104801 & 104803 ** **** Found TwinPrimes based on Prime 17713 **** ** 106277 & 106279 ** **** Found TwinPrimes based on Prime 17827 **** ** 106961 & 106963 ** **** Found TwinPrimes based on Prime 18077 **** ** 108461 & 108463 ** **** Found TwinPrimes based on Prime 18253 **** ** 109517 & 109519 ** **** Found TwinPrimes based on Prime 18307 **** ** 109841 & 109843 ** **** Found TwinPrimes based on Prime 18413 **** ** 110477 & 110479 ** **** Found TwinPrimes based on Prime 18793 **** ** 112757 & 112759 ** **** Found TwinPrimes based on Prime 19267 **** ** 115601 & 115603 ** **** Found TwinPrimes based on Prime 19423 **** ** 116537 & 116539 ** **** Found TwinPrimes based on Prime 19507 **** ** 117041 & 117043 ** **** Found TwinPrimes based on Prime 19583 **** ** 117497 & 117499 ** **** Found TwinPrimes based on Prime 19603 **** ** 117617 & 117619 ** **** Found TwinPrimes based on Prime 19997 **** ** 119981 & 119983 ** **** Found TwinPrimes based on Prime 20123 **** ** 120737 & 120739 ** **** Found TwinPrimes based on Prime 20177 **** ** 121061 & 121063 ** **** Found TwinPrimes based on Prime 20563 **** ** 123377 & 123379 ** **** Found TwinPrimes based on Prime 20717 **** ** 124301 & 124303 ** **** Found TwinPrimes based on Prime 20983 **** ** 125897 & 125899 ** **** Found TwinPrimes based on Prime 21143 **** ** 126857 & 126859 ** **** Found TwinPrimes based on Prime 22073 **** ** 132437 & 132439 ** **** Found TwinPrimes based on Prime 22447 **** ** 134681 & 134683 ** **** Found TwinPrimes based on Prime 22853 **** ** 137117 & 137119 ** **** Found TwinPrimes based on Prime 23447 **** ** 140681 & 140683 ** **** Found TwinPrimes based on Prime 23473 **** ** 140837 & 140839 ** **** Found TwinPrimes based on Prime 23537 **** ** 141221 & 141223 ** **** Found TwinPrimes based on Prime 23917 **** ** 143501 & 143503 ** **** Found TwinPrimes based on Prime 24337 **** ** 146021 & 146023 ** **** Found TwinPrimes based on Prime 24677 **** ** 148061 & 148063 ** **** Found TwinPrimes based on Prime 25037 **** ** 150221 & 150223 ** **** Found TwinPrimes based on Prime 25147 **** ** 150881 & 150883 ** **** Found TwinPrimes based on Prime 25693 **** ** 154157 & 154159 ** **** Found TwinPrimes based on Prime 25847 **** ** 155081 & 155083 ** **** Found TwinPrimes based on Prime 25867 **** ** 155201 & 155203 ** **** Found TwinPrimes based on Prime 26113 **** ** 156677 & 156679 ** **** Found TwinPrimes based on Prime 26203 **** ** 157217 & 157219 ** **** Found TwinPrimes based on Prime 26357 **** ** 158141 & 158143 ** **** Found TwinPrimes based on Prime 26393 **** ** 158357 & 158359 ** **** Found TwinPrimes based on Prime 26813 **** ** 160877 & 160879 ** **** Found TwinPrimes based on Prime 26927 **** ** 161561 & 161563 ** **** Found TwinPrimes based on Prime 26987 **** ** 161921 & 161923 ** **** Found TwinPrimes based on Prime 27437 **** ** 164621 & 164623 ** **** Found TwinPrimes based on Prime 27617 **** ** 165701 & 165703 ** **** Found TwinPrimes based on Prime 27767 **** ** 166601 & 166603 ** **** Found TwinPrimes based on Prime 28513 **** ** 171077 & 171079 ** **** Found TwinPrimes based on Prime 28627 **** ** 171761 & 171763 ** **** Found TwinPrimes based on Prime 28703 **** ** 172217 & 172219 ** **** Found TwinPrimes based on Prime 28753 **** ** 172517 & 172519 ** **** Found TwinPrimes based on Prime 28837 **** ** 173021 & 173023 ** **** Found TwinPrimes based on Prime 29297 **** ** 175781 & 175783 ** **** Found TwinPrimes based on Prime 29327 **** ** 175961 & 175963 ** **** Found TwinPrimes based on Prime 29803 **** ** 178817 & 178819 ** **** Found TwinPrimes based on Prime 29983 **** ** 179897 & 179899 ** **** Found TwinPrimes based on Prime 30133 **** ** 180797 & 180799 ** **** Found TwinPrimes based on Prime 30293 **** ** 181757 & 181759 ** **** Found TwinPrimes based on Prime 30553 **** ** 183317 & 183319 ** **** Found TwinPrimes based on Prime 30817 **** ** 184901 & 184903 ** **** Found TwinPrimes based on Prime 31063 **** ** 186377 & 186379 ** **** Found TwinPrimes based on Prime 31223 **** ** 187337 & 187339 ** **** Found TwinPrimes based on Prime 31477 **** ** 188861 & 188863 ** **** Found TwinPrimes based on Prime 31573 **** ** 189437 & 189439 ** **** Found TwinPrimes based on Prime 31883 **** ** 191297 & 191299 ** **** Found TwinPrimes based on Prime 32057 **** ** 192341 & 192343 ** **** Found TwinPrimes based on Prime 32077 **** ** 192461 & 192463 ** **** Found TwinPrimes based on Prime 32083 **** ** 192497 & 192499 ** **** Found TwinPrimes based on Prime 32323 **** ** 193937 & 193939 ** **** Found TwinPrimes based on Prime 32713 **** ** 196277 & 196279 ** **** Found TwinPrimes based on Prime 32933 **** ** 197597 & 197599 ** **** Found TwinPrimes based on Prime 32993 **** ** 197957 & 197959 ** **** Found TwinPrimes based on Prime 33037 **** ** 198221 & 198223 ** **** Found TwinPrimes based on Prime 33073 **** ** 198437 & 198439 ** **** Found TwinPrimes based on Prime 33637 **** ** 201821 & 201823 ** **** Found TwinPrimes based on Prime 33773 **** ** 202637 & 202639 ** **** Found TwinPrimes based on Prime 34667 **** ** 208001 & 208003 ** **** Found TwinPrimes based on Prime 35053 **** ** 210317 & 210319 ** **** Found TwinPrimes based on Prime 35747 **** ** 214481 & 214483 ** **** Found TwinPrimes based on Prime 35753 **** ** 214517 & 214519 ** **** Found TwinPrimes based on Prime 36263 **** ** 217577 & 217579 ** **** Found TwinPrimes based on Prime 36923 **** ** 221537 & 221539 ** **** Found TwinPrimes based on Prime 36943 **** ** 221657 & 221659 ** **** Found TwinPrimes based on Prime 37223 **** ** 223337 & 223339 ** **** Found TwinPrimes based on Prime 37307 **** ** 223841 & 223843 ** **** Found TwinPrimes based on Prime 37537 **** ** 225221 & 225223 ** **** Found TwinPrimes based on Prime 37657 **** ** 225941 & 225943 ** **** Found TwinPrimes based on Prime 38273 **** ** 229637 & 229639 ** **** Found TwinPrimes based on Prime 38327 **** ** 229961 & 229963 ** **** Found TwinPrimes based on Prime 38903 **** ** 233417 & 233419 ** **** Found TwinPrimes based on Prime 39163 **** ** 234977 & 234979 ** **** Found TwinPrimes based on Prime 39727 **** ** 238361 & 238363 ** **** Found TwinPrimes based on Prime 40343 **** ** 242057 & 242059 ** **** Found TwinPrimes based on Prime 40693 **** ** 244157 & 244159 ** **** Found TwinPrimes based on Prime 40903 **** ** 245417 & 245419 ** **** Found TwinPrimes based on Prime 40927 **** ** 245561 & 245563 ** **** Found TwinPrimes based on Prime 41333 **** ** 247997 & 247999 ** ... Notes: * There is a way to test the candidacy of q for TwinPrimes generation directly using q rather than a via ModularArithmetic. Mod (q,p') x Mod (a,p') = p'1 for all primes p' < q But I am too lazy to implement it. Find an efficient way of determining that a6 & a+6 are coprime to (q2)! and you will potentially have a formulaic method for generating twin primes. That's all I have so far and can't think of a way to proceed any further. Thank you for your time and all the replies. Last fiddled with by a1call on 20181104 at 23:22 
20181105, 00:13  #11  
"Forget I exist"
Jul 2009
Dumbassville
8,369 Posts 
Quote:
Code:
my(p=6); parforprime (q=19^0,5^5,(q2)!,e,a=(e1)/q; if(gcd(ap,a+pe)==1, c=(a+p)*qe; d=e(ap)*q; print("\n**** Found TwinPrimes based on Prime ",q," ****"); print("** ",c," & ",d," **"); );) Last fiddled with by science_man_88 on 20181105 at 00:15 

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