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475 results from messages in primenumbers

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  • The 6 selfridges test fails with [2331286189, 16869702]
    paulunderwood@... Oct 17
  • n=18971;P=18090;Q=17321; gives a counterexample, which I should have found earlier had I not programmed Pari/GP inefficiently Paul
    paulunderwood@... Oct 14
  • { tst(n,P,Q)=(1 <6000. Can you find a counterexample for odd n? Paul -- hoping the Gremlins are hungry this month.
    paulunderwood@... Oct 12
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  • Colin, it is not know that are an infinitude of primes of the form a^2+1, "a" integer: Searching The Net will reveal information about the conjecture, Paul
    paulunderwood@... Sep 26
  • Hey Colin, Searching for the yahoo! primenumbers archive for Wojciech Florek, who had pages of these numbers (b^k-b-1), is fruitless as it leads to dead links. However with the magic of The Way Back Machine I found a link: https://web.archive.org/web/20060306043659/http://perta.fizyka.amu.edu.pl/pnq/prp1.html You can also search by form: http://www.primenumbers.net/prptop/prptop...
    paulunderwood@... Sep 26
  • A snapshot of the top5000 shows: 3184a 2190441873165*2^1290000-1 388342 L4128 2015 3185a 2188771777845*2^1290000-1 388342 L4128 2015 3186a 2187066147387*2^1290000-1 388342 L3985 2015 .... 4993 2862479727*2^1290000-1 388339 L3204 2012 4994 835738017*2^1290000-1 388338 L596 2012 4995 45340243*2^1290000+1 388337 L3494 2014 So PrimeGrid is about to go into tail-eating mode for their...
    paulunderwood@... Sep 10
  • http://primes.utm.edu/primes/page.php?id=120169 http://primes.utm.edu/primes/page.php?id=120170 these tri-megaprimes are unlikely to be prime http://primes.utm.edu/primes/page.php?id=120171 is testable in a reasonable amount of time Paul
    paulunderwood@... Jul 30
  • To add to Jack's reply: https://en.wikipedia.org/wiki/Generalized_taxicab_number Paul
    paulunderwood@... Jul 29
  • Hot on the heels of the last one from November, Karsten Klopffleisch of PrimeGrid has found a new mega-prime, the largest to date found by PrimeGrid: 3*2^11731850-1 (3,531,640 decimal digits) http://primes.utm.edu/primes/page.php?id=119571 Paul
    paulunderwood@... Mar 18
  • Generalizing: {tst(a,k)=local(n=a^2+k);Mod(Mod(1,n)*(L+a),L^2+1)^(n+1)==a^2+1;} Clearly gcd(a,k)==1 is needed and n==3 (mod 4) and a>1. In the light of n=32239;a=63;k=28270; I further stipulate gcd(k-1,a)==1, In order to overcome the n==3 (mod 4) limitation, I propose the following test: {tst(a,k,x)=local(n=a^2+k); a>1&&gcd(k-1,a)==1&&gcd(k,a)==1&&kronecker(x^2-4,n)==-1&& Mod(Mod(1...
    paulunderwood@... Feb 4