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 Showing results 1 to 25 of 154 Search took 0.03 seconds. Search: Posts Made By: JeppeSN
 Forum: Miscellaneous Math 2020-09-13, 09:34 Replies: 8 Views: 336 Posted By JeppeSN How? For example, 7 divides 70, but s(7) = 2*7^2... How? For example, 7 divides 70, but s(7) = 2*7^2 - 1 = 97 does not divide s(70) = 2*70^2 - 1 = 9799. Clearly enough, 97 divides 9797, hence 97 leaves a remainder of 2 when dividing into 9799? It...
 Forum: Information & Answers 2020-09-08, 08:09 Replies: 4 Views: 321 Posted By JeppeSN 16777216 = 2^24. Note that 2^16777216 + 1 =... 16777216 = 2^24. Note that 2^16777216 + 1 = F(24) is the 24th Fermat number. No factors are known. You are probably searching for one. However M(16777216) = 2^16777216 - 1 =...
 Forum: Math 2020-09-02, 10:40 Replies: 3 Views: 1,356 Posted By JeppeSN I wrote that OEIS entry. Did you ever complete... I wrote that OEIS entry. Did you ever complete that ABC file to 2976221 or beyond? /JeppeSN
 Forum: FactorDB 2020-09-01, 11:43 Replies: 3 Views: 327 Posted By JeppeSN There must be or have been some inconsistence on... There must be or have been some inconsistence on how the precedence is when the parentheses are not explicit. If you type (10^79-181)%((10^79-1)/9) you come to the fully factored 79-digit...
 Forum: Proth Prime Search 2020-09-01, 08:44 Replies: 25 Views: 3,400 Posted By JeppeSN One reason for doing very tiny k is that they are... One reason for doing very tiny k is that they are aesthetically more pleasing. Another reason is that the probability that each prime you find, will divide a Fermat number or a generalized Fermat...
 Forum: Information & Answers 2020-08-17, 21:32 Replies: 38 Views: 6,818 Posted By JeppeSN There are infinitely many primes of the form 4*x... There are infinitely many primes of the form 4*x + 1. (https://math.stackexchange.com/questions/244915/) (This is more elementary than the more general Dirichlet theorem on arithmetic progressions...
 2020-08-17, 20:49 Replies: 5 Views: 832 Posted By JeppeSN Oops, that is right. It should have been 2^n-2... Oops, that is right. It should have been 2^n-2 for n prime (http://factordb.com/index.php?query=2%5En-2&use=n&n=2&VP=on&EV=on&OD=on&PR=on&FF=on&PRP=on&CF=on&U=on&C=on&perpage=200&format=1&sent=Show),...
 Forum: XYYXF Project 2020-08-17, 09:26 Replies: 2 Views: 253 Posted By JeppeSN Thanks, that sounds like the explanation! So... Thanks, that sounds like the explanation! So it is n^k + k^n where either 1 < k ≤ n or 1 = k = n-1. It is not really important if we include that exceptional case, or not. There are similar...
 Forum: Math 2020-08-17, 09:00 Replies: 6 Views: 592 Posted By JeppeSN If I understand correctly, this PARI method... If I understand correctly, this PARI method implements it: LLFermat(m) = v=Mod(5,2^(2^m)+1);for(i=1,2^m-2,v=v^2-2);v==0 The way I understand Pépin's test, is: Pepin(m) =...
 Forum: XYYXF Project 2020-08-16, 11:58 Replies: 2 Views: 253 Posted By JeppeSN 3 as Leyland prime? Sorry if this has been asked before. OEIS has the following two sequences: (A076980) Leyland numbers: 3, together with numbers expressible as n^k + k^n nontrivially, i.e., n,k > 1 (to avoid n =...
 Forum: PARI/GP 2020-08-16, 11:02 Replies: 13 Views: 915 Posted By JeppeSN I thought the problem would go away if you... I thought the problem would go away if you shifted away from zero (where the floating point number representation can shift almost arbitrarily), but it still cannot do any of: solve(x=-1, 2, x^3)...
 2020-08-16, 10:34 Replies: 5 Views: 832 Posted By JeppeSN Agree with Batalov; for proving primality of M_p,... Agree with Batalov; for proving primality of M_p, since the full factorization of M_p + 1 is trivial, we do not gain anything from the factorization of M_p - 1. Of course, it may be fun to find...
 Forum: Conjectures 'R Us 2020-08-05, 17:17 Replies: 78 Sticky: PRPnet Servers for CRUS Views: 14,584 Posted By JeppeSN Thank you for all the work you did on these two... Thank you for all the work you did on these two k! I will write a post in this forum if a prime is ever located in one of these two series. /JeppeSN
 Forum: Conjectures 'R Us 2020-08-05, 17:12 Replies: 7 Views: 938 Posted By JeppeSN That private BOINC server now uses the residues... That private BOINC server now uses the residues from CRUS for these two k, and double checks your work. And it has a status page now:...
 Forum: Miscellaneous Math 2020-08-04, 15:52 Replies: 26 Views: 1,259 Posted By JeppeSN You consider d(N) as the difference between the... You consider d(N) as the difference between the number of odd natural numbers under N and the number of even natural numbers under N. Then d(N) does not converge for N tending to infinity, in the...
 Forum: Miscellaneous Math 2020-08-04, 01:06 Replies: 26 Views: 1,259 Posted By JeppeSN I do see some correct statements above. They... I do see some correct statements above. They should be moved out of this crackpot subforum, by someone. Am I being trolled? /JeppeSN
 2020-08-03, 18:13 Replies: 13 Views: 1,052 Posted By JeppeSN That is true: This PARI/GP function imitates your... That is true: This PARI/GP function imitates your program, with an optional seed argument: findPeriod(p,seed=4)=s=Mod(seed,2^p-1);for(i=1,120000,s=s^2-2);S=s;i=0;until(s==S,S=S^2-2;i++);i ...
 2020-08-03, 17:30 Replies: 13 Views: 1,052 Posted By JeppeSN It is perhaps also interesting to note the... It is perhaps also interesting to note the lengths of the "pre-periods", or offsets. That is the number of terms in the LL sequence preceding the first occurrence of the period. With Batalov's data...
 2020-08-03, 07:33 Replies: 13 Views: 1,052 Posted By JeppeSN Thanks, Batalov, that confirms my suspicion. For... Thanks, Batalov, that confirms my suspicion. For example for p=37 (the first one Viliam Furik's method failed for), we start with: 4 -> 14 -> 194 -> 37634 -> 1416317954 -> (period starts here)...
 2020-08-02, 09:26 Replies: 13 Views: 1,052 Posted By JeppeSN The LL sequence starts 4, 14, 194, ... Since... The LL sequence starts 4, 14, 194, ... Since we calculate modulo 2^p - 1, there are only finitely many values we can hit, so sooner or later we are going to hit a value we have seen before. For...
 Forum: Miscellaneous Math 2020-08-02, 01:02 Replies: 46 Views: 2,918 Posted By JeppeSN Cool. The next one can be relevant for the Top... Cool. The next one can be relevant for the Top 5000 of the Prime Pages (Caldwell). /JeppeSN
 Forum: Math 2020-07-30, 08:35 Replies: 23 Views: 1,481 Posted By JeppeSN For the LCM, with PARI, using... For the LCM, with PARI, using lcm(apply(x->x-1,primes([3,23]))), you get 7920. When you try to find the member from 2^1, 2^2, 2^3, ..., 2^7920 (mod 23#) with the least hammingweight, then nothing...
 Forum: Math 2020-07-29, 19:06 Replies: 23 Views: 1,481 Posted By JeppeSN An improvement (i.e. lower hammingweight) I can... An improvement (i.e. lower hammingweight) I can get with that method, is the multiple 2^2513+1098793. It has pops 8. It is a multiple of 23# / 2. /JeppeSN
 Forum: Math 2020-07-29, 18:42 Replies: 23 Views: 1,481 Posted By JeppeSN I try the first one. With PARI/GP, I try znlog(j,... I try the first one. With PARI/GP, I try znlog(j, Mod(2, 3 * 5 * 7 * 11 * 13 * 17 * 19 * 23)) for all j = -1, -2, -3, ... The first time it gives anything, is for j = -69613. Then my multiple is...
 Forum: Math 2020-07-28, 16:49 Replies: 23 Views: 1,481 Posted By JeppeSN https://oeis.org/A091317 says these primes have... https://oeis.org/A091317 says these primes have density 7/24. /JeppeSN
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