[QUOTE=ewmayer;475535]Re. my previous post about c5.9xlarge timings, I should clarify - the 2.4 msec/iter @4096K I got was @16 threads, more threads no help. Similar for ATH's 3.0 ms/iter @4608K, which best-time was @18 threads, again any more hurt rather than helped. Not being a regular AWS user, can someone tell me - the c5.9large has 36 (logical) cores, would running 2 such 16-or-18-threaded jobs side-by-side to more fully utilize said cores cost any more than just one job?[/QUOTE]

You're basically seeing 36 hyperthreads on a single 18 core CPU. When I benchmarked the small c5 instance types, using the hyperthreads gave a slight advantage for mprime.

[QUOTE=ATH;475537]

Still no factor of 2[sup]p[/sup] - 3 (twin prime)[/QUOTE]
I think that would qualify as a miracle.:devil::devil:

[QUOTE=Batalov;475611]Simply running PRP will take less than 46 hours, Andreas! If you still don't have a factor - run PRP.[/QUOTE]

That sparked the idea in me too... just started out a PRP run of 2^XXXXXXXX-3 - it says it'll take 48-49 hours. Why not. :smile:

[QUOTE=a1call;475654]I think that would qualify as a miracle.:devil::devil:[/quOTE]

it did happen once before M[SUB]3[/SUB]-2 is prime. :whistle:

[QUOTE=Madpoo;475668]That sparked the idea in me too... just started out a PRP run of 2^XXXXXXXX-3 - it says it'll take 48-49 hours. Why not. :smile:[/QUOTE]

I actually already started it earlier. ETA ~40h now.

[QUOTE=rudy235;475674]it did happen once before M[SUB]3[/SUB]-2 is prime. :whistle:[/QUOTE]

Only for 2 of the first Mersenne primes, because primes are very abundant there.
M2-2 = 2^3-3 = 5
M3-2 = 2^5-3 = 29

[QUOTE=ATH;475688]Only for 2 of the first Mersenne primes, because primes are very abundant there.
M2-2 = 2^3-3 = 5
M3-2 = 2^5-3 = 29[/QUOTE]

I know. But the first case M[SUB]2[/SUB]-3 (=5) is totally unique. There will never be another prime ending in 5.

M[SUB]3[/SUB] -3 however ends in 9 and about 25% of all primes end in 9.

BTW, I am not affirming that there is indeed another 2[SUP]p[/SUP] -3 that is prime, just that the possibility is >0 if P mod 4 = 1

Is it "type 1" or "type 3"?
 

[QUOTE=rudy235;475692]BTW, I am not affirming that there is indeed another 2[SUP]p[/SUP] -3 that is prime, just that the possibility is >0 if P mod 4 = 1[/QUOTE]

Why the restriction P = 1 mod 4?

At least no one is looking for a triplet, which implies that the editing of post 149 was justified.:smile:
Thanks for the leak.:smile:

I have no entry in the Predict M50 thread.
Can I post one?

I don't have a horse in that race,either, but I believe voting is locked, pending verification.

[QUOTE=ATH;475687]I actually already started it earlier. ETA ~40h now.[/QUOTE]

Ah, in that case... okay, I stopped mine. :smile: